Added release notes for 2.2.4.

Author: rstam

Release Notes/Release Notes v2.2.4.md

@@ -1,3 +1,19 @@
 # .NET Driver Version 2.2.4 Release Notes
 
-This is a placeholder for the release notes for the next release.
+This is a patch release which fixes some bugs reported since 2.2.3 was released.
+
+An online version of these release notes is available at:
+
+https://github.com/mongodb/mongo-csharp-driver/blob/v2.2.x/Release%20Notes/Release%20Notes%20v2.2.4.md
+
+The full list of JIRA issues resolved in this release is available at:
+
+https://jira.mongodb.org/issues/?jql=project%20%3D%20CSHARP%20AND%20fixVersion%20%3D%202.2.4%20ORDER%20BY%20key%20ASC
+
+Documentation on the .NET driver can be found at:
+
+http://mongodb.github.io/mongo-csharp-driver/
+
+Upgrading
+
+There are no known backwards breaking changes in this release.