docs/cql: fix UDT example to use frozen<address>

The 'address' UDT contains a nested collection (map<text, frozen<phone>>),
so it must be frozen when used as a column type. Non-frozen UDTs with
nested non-frozen collections are not supported.

(cherry picked from commit d13a56be2e)

docs/cql/types.rst

@@ -507,7 +507,7 @@ For example::
 
   CREATE TABLE superheroes (
        name frozen<full_name> PRIMARY KEY,
-       home address
+       home frozen<address>
   );
 
 .. note::