Bumped date on release notes and added an extra note.

doc/src/releasenotes.md

@@ -1,17 +1,19 @@
 
 ## MIOpen Release notes
 
-### 12/14/2018 [ 1.7.0 ]
+### 12/19/2018 [ 1.7.0 ]
 
 - This release contains general bug fixes and an updated performance database
 - Group convolutions backwards weights performance has been improved
 - Logging across the library has been improved
+- Performance database has been updated
 
 
 Changes:
 
 - Fixed logging issues with group convolution and pooling
 - Fixed sphinx version issue in document generation
+- Fixed issues with corrupt entries in performance database
 - Removed external dependency on libSSL and libCrypto
 - Added support for large image backwards weights in direct convolution
 - Added fp16 support for RNNs on the HIP backend