Add link to list of encodings on the Encodings page

Author: samcv

doc/Type/Encoding.pod6

@@ -10,7 +10,7 @@ The C<Encoding> role is implemented by objects that provide a character
 encoding, such as ASCII or UTF-8. Besides being implemented by the built-in
 character encodings, it may also be implemented by users to provide new
 encodings. Instances of objects doing this role are typically obtained using
-C<Encoding::Registry>.
+C<Encoding::Registry>. For a list of supported encodings, see L<IO::Handle|/type/IO::Handle#method_encoding>
 
 =head1 Methods