Regex: Add more info on matching Unicode Properties.

Show how to match not only the General Categories
but also the values of Unicode Properties.

doc/Language/regexes.pod6

@@ -203,10 +203,17 @@ Predefined subrules:
 
 The character classes so far are mostly for convenience; a more systematic
 approach is the use of Unicode properties. They are called in the form C<<
-<:property> >>, where C<property> can be a short or long Unicode property
-name.
+<:property> >>, where C<property> can be a short or long Unicode General
+Category name. These use pair syntax.
 
-The following list is stolen from the Perl 5
+To match against a specific value for a Unicode Property:
+
+    "a".uniprop('Script') # Latin
+    "a" ~~ / <:Script<Latin>> /
+    "a".uniprop('Block') # Basic Latin
+    "a" ~~ / <:Block('Basic Latin') /
+
+The following list of Unicode General Categories is stolen from the Perl 5
 L<perlunicode|http://perldoc.perl.org/perlunicode.html> documentation:
 
 =begin table