Added a link to native types

Since most of the other related issues have been addressed, including
the early issue #1376, this closes #1879

Author: JJ

doc/Language/functions.pod6

@@ -63,7 +63,7 @@ By default, subroutines are L<lexically scoped|/syntax/my>. That is,
 C<sub foo {...}> is the same as C<my sub foo {...}> and is only
 defined within the current scope.
 
-=begin code :allow<L>
+=begin code
 sub escape($str) {
     # Puts a slash before non-alphanumeric characters
     S:g[<-alpha -digit>] = "\\$/" given $str
@@ -84,7 +84,8 @@ say escape 'foo#bar?'; # OUTPUT: «foo\#bar\?␤»
 say escape 'foo#bar?'; # OUTPUT: «foo\#bar\?␤»
 =end code
 
-Subroutines don't have to be named. If unnamed, they're called I<anonymous> subroutines.
+Subroutines don't have to be named. If unnamed, they're called I<anonymous>
+subroutines.
 
     say sub ($a, $b) { $a ** 2 + $b ** 2 }(3, 4) # OUTPUT: «25␤»
 
@@ -853,7 +854,7 @@ a 1;        # OUTPUT: «Int 1␤Any 2␤Back in Int with 5␤»
 
 Here, C<a 1> calls the most specific C<Int> candidate first, and C<callwith>
 re-dispatches to the less specific C<Any> candidate. Note that although our
-parameter C<$x + 1> is an Int, still we call the next candidate in the chain.
+parameter C<$x + 1> is an C<Int>, still we call the next candidate in the chain.
 
 =head2 sub nextsame
 

doc/Language/nativecall.pod6

@@ -17,7 +17,7 @@ The simplest imaginable use of C<NativeCall> would look something like this:
 The first line imports various traits and types. The next line looks like
 a relatively ordinary Perl 6 sub declaration—with a twist. We use the
 "native" trait in order to specify that the sub is actually defined in a
-native library. The platform-specific extension (e.g., '.so' or '.dll'),
+native library. The platform-specific extension (e.g., C<.so> or C<.dll>),
 as well as any customary prefixes (e.g., 'lib') will be added for you.
 
 The first time you call "some_argless_function", the "libsomething" will be
@@ -29,6 +29,8 @@ that you can do is just adding to this simple pattern of declaring a Perl 6 sub
 naming it after the symbol you want to call and marking it with the "native"
 trait.
 
+You will also need to declare and use native types. Please check L<the native types page|/language/nativetypes> for more information.
+
 =head1 Changing names
 
 Sometimes you want the name of your Perl subroutine to be different from the