fixup now-tested code examples

doc/Language/5to6-nutshell.pod6

@@ -277,7 +277,7 @@ variable holding a code object as an argument:
 first_index { $_ > 5 } @values;
 &first_index($coderef, @values); # (disabling the prototype that parses a
                                      # literal block as the first argument)
-=for code
+=for code :preamble<my @values; my $coderef>
 # Perl 6:
 first { $_ > 5 }, @values, :k;   # the :k makes first return an index
 first $coderef, @values, :k;
@@ -294,7 +294,8 @@ exact equivalent in Perl 5.
 
 =for code :lang<perl5>
 sub foo { say "before"; &bar;     say "after" } # Perl 5
-=for code
+
+=for code :preamble<sub bar() {...}>
 sub foo { say "before"; bar(|@_); say "after" } # Perl 6 - have to be explicit
 
 

doc/Language/subscripts.pod6

@@ -59,7 +59,7 @@ as if they were postcircumfix operators:
 This is really just syntactic sugar that gets turned into the corresponding
 C<{ }> form at compile-time:
 
-    =begin code
+    =begin code :preamble<my %hash;my $var>
     %hash<foo bar>;       # same as %hash{ <foo bar> }
     %hash«foo "$var"»;    # same as %hash{ «foo "$var"» }
     %hash<<foo "$var">>;  # same as %hash{ <<foo "$var">> }