perldelta for Unicode update

Author: khwilliamson

pod/perldelta.pod

@@ -27,6 +27,12 @@ here, but most should go in the L</Performance Enhancements> section.
 
 [ List each enhancement as a =head2 entry ]
 
+=head2 Unicode 16.0 supported
+
+Perl now supports Unicode 16.0
+L<https://www.unicode.org/versions/Unicode16.0.0/> including the changes
+introduced in 15.1 L<https://www.unicode.org/versions/Unicode15.1.0/>.
+
 =head1 Security
 
 XXX Any security-related notices go here. In particular, any security