Several improvements on this page

It actually started with #1566, trying to improve the description of
constants. However, while I was at it, I noticed references to
Synopsis, so I changed a few of them working on #2225.
This also fixes #2226 and, in fact, has generated rakudo/rakudo#2141
for a command line flag that was referenced here and was actually
working on Perl 6 (undocumented). Of course, there was a bit of #2223
and a bit of reflow.

I guess now it's back to work on #1566 or maybe #2225.

doc/Language/5to6-nutshell.pod6

@@ -1,6 +1,6 @@
 =begin pod :tag<convert>
 
-=TITLE Perl 5 to Perl 6 guide - In a Nutshell
+=TITLE Perl 5 to Perl 6 guide - In a nutshell
 
 =SUBTITLE How do I do what I used to do? (Perl 6 in a nutshell)
 
@@ -63,9 +63,13 @@ all at once.
 
 =head1 Syntax
 
+There are a few differences in syntax between the two languages, starting with
+how identifiers are defined.
+
 =head2 Identifiers
 
-In identifiers, Perl 6 allows the use of dashes (C<->), underscores (C<_>), apostrophes (C<'>), and alphanumerics:
+Perl 6 allows the use of dashes (C<->), underscores (C<_>),
+apostrophes (C<'>), and alphanumerics in identifiers, :
 
     sub test-doesn't-hang { ... }
     my $ความสงบ = 42;
@@ -463,27 +467,30 @@ my @array = 4,8,15;
 say @array; #  OUTPUT: «[66 8 15]␤»
 =end code
 
-The underlying Array object of C<@array> is passed, and its first value modified inside the declared routine.
+The underlying Array object of C<@array> is passed, and its first value modified
+inside the declared routine.
 
-In Perl 5, the syntax for dereferencing an entire reference is the
-type-sigil and curly braces, with the reference inside the curly braces. In Perl 6, this concept simply does not apply, since the I<reference> metaphor does not really apply.
+In Perl 5, the syntax for dereferencing an entire reference is the type-sigil
+and curly braces, with the reference inside the curly braces. In Perl 6, this
+concept simply does not apply, since the I<reference> metaphor does not really
+apply.
 
 In Perl 5, the arrow operator, C«->» , is used for single access to a
-composite's reference or to call a sub through its reference. In Perl 6,
-the dot operator C<.> is always used for object methods, but the rest does not really apply.
+composite's reference or to call a sub through its reference. In Perl 6, the dot
+operator C<.> is always used for object methods, but the rest does not really
+apply.
 
 =for code :lang<perl5>
 # Perl 5
     say $arrayref->[7];
     say $hashref->{'fire bad'};
     say $subref->($foo, $bar);
 
-In relatively recent versions of Perl 5 (5.20 and later), a new feature allows the use of the arrow
-operator for dereferencing:  see
-L<Postfix Dereferencing|http://search.cpan.org/~shay/perl-5.20.1/pod/perl5200delta.pod#Experimental_Postfix_Dereferencing>. This
-can be used to create an array from a scalar. This operation is
-usually called I<decont>, as in decontainerization, and in Perl 6
-methods such as C<.list> and C<.hash> are used:
+In relatively recent versions of Perl 5 (5.20 and later), a new feature allows
+the use of the arrow operator for dereferencing:  see L<Postfix Dereferencing|http://search.cpan.org/~shay/perl-5.20.1/pod/perl5200delta.pod#Experimental_Postfix_Dereferencing>.
+This can be used to create an array from a scalar. This operation is usually
+called I<decont>, as in decontainerization, and in Perl 6 methods such as
+C<.list> and C<.hash> are used:
 
 =for code :lang<perl5>
 # Perl 5.20
@@ -504,11 +511,12 @@ The "Zen" slice does the same thing:
     my @a = $contains-an-array[];
     my %h = $contains-a-hash{};
 
-See L<the "Containers" section of the documentation|/language/containers> for more information.
+See L<the "Containers" section of the documentation|/language/containers> for
+more information.
 
 =head1 Operators
 
-See L<S03/Operators|https://design.perl6.org/S03.html#Overview>
+See L<the documentation for operators|/language/operators>
 for full details on all operators.
 
 Unchanged:
@@ -559,7 +567,7 @@ type of its arguments.
 While the operator has not changed, the rules for what exactly is matched
 depend on the types of both arguments, and those rules are far from
 identical in Perl 5 and Perl 6. See L<~~|/routine/~~> and
-L<S03/Smartmatching|https://design.perl6.org/S03.html#Smart_matching>
+L<the smartmatch operator|/language/operators#index-entry-smartmatch_operator>
 
 =head2 C<& | ^> String Bitwise ops
 =head2 C<& | ^> Numeric Bitwise ops
@@ -708,19 +716,22 @@ operators. They have been replaced by C<ff> and C<fff>.
 
 =head2 String interpolation
 
-In Perl 5, C<"${foo}s"> deliminates a variable name from regular text next to it.
-In Perl 6, simply extend the curly braces to include the sigil too: C<"{$foo}s">.
-This is in fact a very simple case of interpolating an expression.
+In Perl 5, C<"${foo}s"> deliminates a variable name from regular text next to
+it. In Perl 6, simply extend the curly braces to include the sigil too:
+C<"{$foo}s">. This is in fact a very simple case of interpolating an expression.
 
 =head1 Compound Statements
 
+These statements include conditionals and loops.
+
 =head2 Conditionals
 
 =head3 C<if> C<elsif> C<else> C<unless>
 
 Mostly unchanged; parentheses around the conditions are now optional, but if
 used, must not immediately follow the keyword, or it will be taken as a function
-call instead.  Binding the conditional expression to a variable is also a little different:
+call instead.  Binding the conditional expression to a variable is also a little
+different:
 
 =for code :lang<perl5>
 if (my $x = dostuff()) {...}  # Perl 5
@@ -774,7 +785,8 @@ See also the warnings on the smartmatch op above.
 
 Mostly unchanged; parentheses around the conditions are now optional, but if
 used, must not immediately follow the keyword, or it will be taken as a function
-call instead.  Binding the conditional expression to a variable is also a little different:
+call instead.  Binding the conditional expression to a variable is also a little
+different:
 
 =for code :lang<perl5>
 while (my $x = dostuff()) {...}  # Perl 5
@@ -830,7 +842,7 @@ repeat {
 =head3 C<for> C<foreach>
 
 Note first this common misunderstanding about the C<for> and C<foreach>
-keywords. Many programmers think that they distinguish between the C-style
+keywords: Many programmers think that they distinguish between the C-style
 three-expression form and the list-iterator form; they do not! In fact,
 the keywords are interchangeable; the Perl 5 compiler looks for the
 semi-colons within the parentheses to determine which type of loop to parse.
@@ -1019,8 +1031,7 @@ $line =~ s/abc/123/;          # Perl 5
 $line ~~ s/abc/123/;          # Perl 6
 
 Alternately, the new C<.match> and C<.subst> methods can be used. Note that
-C<.subst> is non-mutating. See
-L<S05/Substitution|https://design.perl6.org/S05.html#Substitution>.
+L<C<.subst> is non-mutating|/routine/subst>.
 
 =head2 Captures start with 0, not 1
 
@@ -1161,8 +1172,7 @@ else {
     # gracefully handle the fact that the open() failed
 }
 
-=head3 C<base>
-=head3 C<parent>
+=head3 C<base>, C<parent>
 
 Both C<use base> and C<use parent> have been replaced in Perl 6 by the
 C<is> keyword, in the class declaration.
@@ -1188,11 +1198,11 @@ denominator is limited to C<2**64>, after which it will automatically
 upgrade to C<Num> to preserve performance).  If you want a C<Rat> with
 an arbitrary-precision denominator, C<FatRat> is available.
 
-=head3 X<C<constant>|constant>
+=head3 C<constant>
 
-In Perl 6, C<constant> is a declarator for variables, just like C<my>,
-except the variable is permanently locked to the result of its
-initialization expression (evaluated at compile time).
+In Perl 6, C<constant> is a declarator for variables, just like C<my>, except
+the variable is permanently locked to the result of its initialization
+expression (evaluated at compile time).
 
 So, change the C«=>» to C<=>.
 
@@ -1209,7 +1219,7 @@ use constant pi => 4 * atan2(1, 1); # Perl 5
 
 =head3 C<encoding>
 
-TODO Allows you to write your script in non-ascii or non-utf8
+TODO Allows you to write your script in non-ascii or non-utf8.
 
 =head3 C<integer>
 
@@ -1241,9 +1251,7 @@ say Animal.^mro;    # .^ indicates calling a meta-method on the object
 
 =head3 C<utf8>
 
-No longer relevant.
-
-In Perl 6, source code is expected to be in utf8 encoding.
+No longer relevant: in Perl 6, source code is expected to be in utf8 encoding.
 
 =head3 C<vars>
 
@@ -1257,11 +1265,11 @@ before translating into Perl 6.
 =head1 Command-line flags
 
 See
-L<S19/commandline|https://design.perl6.org/S19.html#Command_Line_Elements>
+L<the command line flags that Rakudo uses|https://github.com/rakudo/rakudo/wiki/Running-rakudo-from-the-command-line>
 
 Unchanged:
 
--c -e -h -I -n -p -S -T -v -V
+-c -e -h -I -n -p -v -V
 
 =head3 C<-a>
 
@@ -1323,6 +1331,10 @@ Removed. See L<S19#Removed Syntactic Features|https://design.perl6.org/S19.html#
 
 This is now the default behavior.
 
+=item C<-S>, C<-T>.
+
+This has been eliminated. Several ways to L<replicate "taint" mode are discussed in Reddit|https://www.reddit.com/r/perl6/comments/718z4o/taint_mode_for_perl_6/>.
+
 =head1 File-related operations
 
 =head2 Reading the lines of a text file into an array
@@ -1410,8 +1422,8 @@ probably guessed, you just need to use X<C<PERL6LIB>|PERL6LIB>:
 =for code :lang<shell>
 $ PERL6LIB="/some/module/lib" perl6 program.p6
 
-In Perl 5 one uses the ':' (colon) as a directory separator for C<PERL5LIB>, but in
-Perl 6 one uses the ',' (comma).  For example:
+In Perl 5 one uses the ':' (colon) as a directory separator for C<PERL5LIB>, but
+in Perl 6 one uses the ',' (comma).  For example:
 
 =for code :lang<shell>
 $ export PERL5LIB=/module/dir1:/module/dir2;
@@ -1499,9 +1511,11 @@ If one tries to use C<baz> an "Undeclared routine" error is raised at compile ti
 
 So, how does one recreate the Perl 5 behaviour of being able to selectively
 import functions?  For this one needs to define an C<EXPORT> sub inside the
-module which specifies the functions to be exported and remove the C<module Bar> statement.
+module which specifies the functions to be exported and remove the C<module Bar>
+statement.
 
-The module C<Bar> now is merely a file called C<Bar.pm> with the following contents:
+The module C<Bar> now is merely a file called C<Bar.pm> with the following
+contents:
 
 =begin code :preamble<no strict;>
 use v6.c;
@@ -1719,9 +1733,7 @@ Note that Perl 6 auto-generates a full usage message on error in
 command-line parsing.
 
 
-
-
-=head1 Automated Translation
+=head1 Automated translation
 
 A quick way to find the Perl 6 version of a Perl 5 construct, is to run it
 through an automated translator.
@@ -1739,7 +1751,7 @@ L<https://github.com/Util/Blue_Tiger/>
 
 =head2 Perlito
 
-Online Translator!
+Online translator!
 
 This project is a suite of Perl cross-compilers, including Perl 5-to-6
 translation. It has a web front-end, and so can be used without
@@ -1749,14 +1761,14 @@ L<http://fglock.github.io/Perlito/perlito/perlito5.html>
 
 =head2 Perl-ToPerl6
 
-Jeff Goff's Perl::ToPerl6 module for Perl 5 is designed around
-Perl::Critic's framework. It aims to convert Perl5 to compilable (if not
-necessarily running) Perl 6 code with the bare minimum of changes. Code
-transformers are configurable and pluggable, so you can create and
-contribute your own transformers, and customize existing transformers to
-your own needs. You can install the latest release from CPAN, or follow
-the project live on GitHub. An online converter may become available at
-some point.
+Jeff Goff's
+L<Perl::ToPerl6|https://metacpan.org/release/JGOFF/Perl-ToPerl6-0.03> module for
+Perl 5 is designed around Perl::Critic's framework. It aims to convert Perl5 to
+compilable (if not necessarily running) Perl 6 code with the bare minimum of
+changes. Code transformers are configurable and pluggable, so you can create and
+contribute your own transformers, and customize existing transformers to your
+own needs. You can install the latest release from CPAN, or follow the project
+live on GitHub. An online converter may become available at some point.
 
 =head1 Other sources of translation knowledge