Fix broken link to cx_Oracle documentation

Author: plettich

lib/sqlalchemy/dialects/oracle/cx_oracle.py

@@ -208,7 +208,7 @@
 
 Users of the cx_Oracle dialect are **strongly encouraged** to read through
 cx_Oracle's list of built-in datatype symbols at
-http://cx-oracle.readthedocs.io/en/latest/module.html#types.
+http://cx-oracle.readthedocs.io/en/latest/module.html#database-types.
 Note that in some cases, significant performance degradation can occur when
 using these types vs. not, in particular when specifying ``cx_Oracle.CLOB``.