Update release_notes.md (#844)

release_notes.md

@@ -8,4 +8,6 @@
     * Support AAD authentication in connection string. (#803)
     * Add some convenient POJOs. (#774)
     * Support multiple Azure SignalR Service instances. (#566)
-    * Fix a bug that group name is required when group action is "RemoveAll". (#347)
+    * Fix a bug that group name is required when group action is "RemoveAll". (#347)
+- Bug fix: Handle = character in cookie value (#838)
+- Error handling for in-proc SDK usage inside isolated app. (#824)