Clarifies capturing properties of square brackets in regex

Also clarifies how round brackets work in name capture.

Also take the mystery out of what we are going to see in subrules.

doc/Language/regexes.pod6

@@ -1008,7 +1008,7 @@ The parentheses in regexes perform a double role: they group the regex
 elements inside and they capture what is matched by the sub-regex inside.
 
 To get only the grouping behavior, you can use square brackets C<[ ... ]>
-instead.
+which, by default, don't capture.
 
     if 'abc' ~~ / [a||b] (c) / {
         say ~$0;                # OUTPUT: «c␤»
@@ -1103,9 +1103,16 @@ and slightly verbose, way of naming captures is like this:
         say ~$<myname>      # OUTPUT: «abc␤»
     }
 
+The square brackets in the above example, which don't usually capture, will now capture its grouping
+with the given name.
+
 The access to the named capture, C«$<myname>», is a shorthand for indexing
 the match object as a hash, in other words: C<$/{ 'myname' }> or C«$/<myname>».
 
+We can also use round brackets in the above example, but they will work exactly the same as square brackets.
+The captured group will only be accessible by its name as a key from the match object and not from
+its position in the list with C<$/[0]> or C<$0>.
+
 Named captures can also be nested using regular capture group syntax:
 
     if 'abc-abc-abc' ~~ / $<string>=( [ $<part>=[abc] ]* % '-' ) / {
@@ -1129,7 +1136,7 @@ all named captures:
         }
     }
 
-A more convenient way to get named captures is discussed in
+A more convenient way to get named captures is by using named regex as discussed in
 the L<Subrules|#Subrules> section.
 
 =head2 X«Capture markers: C«<( )>»|regex,<( )>»