Adds publication of variables, closes #2887

Author: JJ

doc/Language/regexes.pod6

@@ -1084,19 +1084,29 @@ levels behaving as elements of that list
         say "Inner: $0[0] and $0[1]";   # OUTPUT: Inner: b and c
     }
 
-If you need to refer to a capture from within another capture, store
-it in a variable first:
+These capture variables are only available outside the regex.
 
 =begin code
 # !!WRONG!! The $0 refers to a capture *inside* the second capture
 say "11" ~~ /(\d) ($0)/; # OUTPUT: «Nil␤»
+=end code
+
+In order to make them available inside the regex, you need to insert a code
+block behind the match; this code block may be empty if there's nothing
+meaningful to do:
 
+=begin code
 # CORRECT: $0 is saved into a variable outside the second capture
-# before it is used inside (the `{}` is needed to update the current match)
+# before it is used inside
 say "11" ~~ /(\d) {} :my $c = $0; ($c)/; # OUTPUT: «｢11｣␤ 0 => ｢1｣␤ 1 => ｢1｣␤»
 say "Matched $c"; # OUTPUT: «␤Matched 1␤»
 =end code
 
+This code block I<publishes> the capture inside the regex, so that it can be
+assigned to other variables or used for subsequent matches
+
+=for code
+say "11" ~~ /(\d) {} $0/; # OUTPUT: «｢11｣␤ 0 => ｢1｣␤»
 
 X<|:my>
 C<:my> helps scoping the C<$c> variable within the regex and beyond; in this