Document &*ARGS-TO-CAPTURE, &*GENERATE-USAGE on the variables page.

Move documentation from Language/create-cli.pod6; cross reference.
This also fixes broken links to:

- /language/&*ARGS-TO-CAPTURE
- /language/&*GENERATE-USAGE

doc/Language/create-cli.pod6

@@ -312,17 +312,11 @@ during testing of a command line interface of a script):
           !! &*ARGS-TO-CAPTURE(&main, @args)
     }
 
-Note that the dynamic variable L<&*ARGS-TO-CAPTURE> is available to perform
+Note that the dynamic variable L<C<&*ARGS-TO-CAPTURE>|/language/variables#&*ARGS-TO-CAPTURE>
+is available to perform
 the default command line arguments to C<Capture> processing so you don't
 have to reinvent the whole wheel if you don't want to.
 
-X<|&*ARGS-TO-CAPTURE>
-=head2 &*ARGS-TO-CAPTURE
-
-A dynamic variable available inside any custom C<ARGS-TO-CAPTURE> subroutine
-that can be used to perform the default argument parsing.  Takes the same
-parameters as are expected of the custom C<ARGS-TO-CAPTURE> subroutine.
-
 =head1 Intercepting usage message generation (2018.10, v6.d and later)
 
 You can replace or augment the default way of usage message generation
@@ -357,17 +351,11 @@ You can also use multi subroutines to create the same effect:
         &*GENERATE-USAGE(&main, |capture)
     }
 
-Note that the dynamic variable L<&*GENERATE-USAGE> is available to perform
+Note that the dynamic variable L<C<&*GENERATE-USAGE>|/language/variables#&*GENERATE-USAGE>
+is available to perform
 the default usage message generation so you don't have to reinvent the
 whole wheel if you don't want to.
 
-X<|&*GENERATE-USAGE>
-=head2 &*GENERATE-USAGE
-
-A dynamic variable available inside any custom C<GENERATE-USAGE> subroutine
-that can be used to perform the default usage message creation.  Takes the
-same parameters as are expected of the custom C<GENERATE-USAGE> subroutine.
-
 =head1 Intercepting MAIN calling (before 2018.10, v6.e)
 
 An older interface enabled one to intercept the calling to C<MAIN> completely.
@@ -389,4 +377,4 @@ then the support for the old interface can be removed from the module.
 
 =end pod
 
-# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6
+# vim: expandtab softtabstop=4 shiftwidth=4 ft=perl6

doc/Language/variables.pod6

@@ -1241,6 +1241,22 @@ when C<@*ARGS> is not empty.
 
 C<@*ARGS> contains the arguments from the command line.
 
+X<|&*ARGS-TO-CAPTURE>
+=head4 C<&*ARGS-TO-CAPTURE>
+
+A dynamic variable available inside any custom
+L<C<ARGS-TO-CAPTURE>|/language/create-cli#sub_ARGS-TO-CAPTURE> subroutine
+that can be used to perform the default argument parsing.  Takes the same
+parameters as are expected of the custom C<ARGS-TO-CAPTURE> subroutine.
+
+X<|&*GENERATE-USAGE>
+=head4 C<&*GENERATE-USAGE>
+
+A dynamic variable available inside any custom
+L<C<GENERATE-USAGE>|/language/create-cli#sub_GENERATE-USAGE> subroutine
+that can be used to perform the default usage message creation.  Takes the
+same parameters as are expected of the custom C<GENERATE-USAGE> subroutine.
+
 X<|$*IN>X<|$*OUT>X<|$*ERR>
 =head3 Special filehandles: C<STDIN>, C<STDOUT> and C<STDERR>