Document :our

Also adds :my and :our to index. Examples provided by the OP (thanks,
@lefth) and
[roast](https://github.com/perl6/roast/blob/d1baf2e7a3e56cd6619c46040d04ed6daebc1d02/S05-modifier/my.t). There
does not seem to be many other uses of :our in the wild. Anyway, this
closes #1475.

Author: JJ

doc/Language/regexes.pod6

@@ -1026,12 +1026,29 @@ it in a variable first:
     say "Matched $c"; # OUTPUT: «␤Matched 1␤»
 
 
+X<|:my>
 C<:my> helps scoping the C<$c> variable within the regex and beyond; in this case we can use it in the next sentence to show what has been matched inside the regex. This can be used for debugging inside regular expressions, for instance:
 
-    my $paragraph="line\nline2\nline3"; 
+    my $paragraph="line\nline2\nline3";
     $paragraph ~~ rx| :my $counter = 0; ( \V* { ++$counter } ) *%% \n |;
     say "Matched $counter lines"; # OUTPUT: «Matched 3 lines␤»
 
+X<|:our>
+The C<:our>, similarly to L<C<our>|/syntax/our> in classes, can be used in L<Grammar>s to declare variables that can be accessed, via its fully qualified name, from outside the grammar:
+
+=begin code
+grammar HasOur {
+    token TOP {
+        :our $our = 'þor';
+        $our \s+ is \s+ mighty
+    }
+}
+
+say HasOur.parse('þor is mighty'); # OUTPUT: «｢þor is mighty｣␤»
+say $HasOur::our;                  # OUTPUT: «þor␤»
+=end code
+
+Once the parsing has been done successfully, we use the FQN name of the C<$our> variable to access its value, that can be none other than C<þor>
 
 =head2 X<Named captures|regex, Named captures>