update changelog with results of #86 and #56

Author: mattsb42-aws

CHANGELOG.rst

@@ -2,6 +2,17 @@
 Changelog
 *********
 
+1.3.8 -- 2018-xx-xx
+===================
+
+Minor
+-----
+
+* Add support to remove clients from :ref:`KMSMasterKeyProvider` client cache if they fail to connect to endpoint.
+  `#86 <https://github.com/aws/aws-encryption-sdk-python/pull/86>`_
+* Add support for SHA384 and SHA512 for use with RSA OAEP wrapping algorithms.
+  `#56 <https://github.com/aws/aws-encryption-sdk-python/issues/56>`_
+
 1.3.7 -- 2018-09-20
 ===================