Added release notes for 1.6.1.

CSharpDriver-2010.sln

@@ -44,6 +44,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Release Notes", "Release No
 		Release Notes\Release Notes v1.4.2.md = Release Notes\Release Notes v1.4.2.md
 		Release Notes\Release Notes v1.4.md = Release Notes\Release Notes v1.4.md
 		Release Notes\Release Notes v1.5.md = Release Notes\Release Notes v1.5.md
+		Release Notes\Release Notes v1.6.1.md = Release Notes\Release Notes v1.6.1.md
 		Release Notes\Release Notes v1.6.md = Release Notes\Release Notes v1.6.md
 	EndProjectSection
 EndProject

Release Notes/Release Notes v1.6.1.md

@@ -0,0 +1,68 @@
+C# Driver Version 1.6.1 Release Notes
+=====================================
+
+This is a minor release containing a few bug fixes, particularly related to ReadPreference support
+and sending commands to secondaries.
+
+An online version of these release notes is available at:
+
+https://github.com/mongodb/mongo-csharp-driver/blob/master/Release%20Notes/Release%20Notes%20v1.6.1.md
+
+File by file change logs are available at:
+
+https://github.com/mongodb/mongo-csharp-driver/blob/master/Release%20Notes/Change%20Log%20v1.6.1-Bson.txt
+https://github.com/mongodb/mongo-csharp-driver/blob/master/Release%20Notes/Change%20Log%20v1.6.1-Driver.txt
+
+The full list of JIRA issues resolved in this release is available at:
+
+https://jira.mongodb.org/secure/IssueNavigator.jspa?mode=hide&requestId=12609
+
+Changes to ReadPreference
+-------------------------
+
+The implementation of ReadPreference has been changed to more accurately follow the ReadPreference spec:
+
+http://docs.mongodb.org/manual/applications/replication/#read-preference
+
+The changes are:
+
+- SecondaryPreferred only uses the Primary if no secondaries are available (regardless of latency)
+- SecondayAcceptableLatency is now configurable
+- when sending queries to mongos:
+    - ReadPreference.Primary is encoded setting the SlaveOk bit on the wire protocol to 0
+	- ReadPreference.SecondaryPreferred (without tags) is encoded setting the SlaveOk bit on the wire protocol to 1
+	- all other ReadPreferences are encoded using $readPreference on the wire
+    - $query is now encoded before $readPreference as required by mongos
+- commands now correctly use the collection settings (they were using the database settings)
+
+Sending commands to secondaries
+-------------------------------
+
+Only a limited set of commands are now allowed to be sent to secondaries. All other commands
+will be sent to the primary regardless of the ReadPreference you specify. The commands
+that can be sent to secondaries are:
+
+- aggregate
+- collStats
+- count
+- dbStats
+- distinct
+- geoNear
+- geoSearch
+- geoWalk
+- group
+- mapReduce (but *only* if using Inline results)
+
+The corresponding helper methods in the C# driver are:
+
+- MongoCollection.Aggregate
+- MongoCollection.GetStats
+- MongoCollection.Count, MongoCursor.Count and MongoCursor.Size
+- MongoDatabase.GetStats
+- MongoCollection.Distinct
+- MongoCollection.GeoNear and MongoCollection.GeoNearAs
+- MongoCollection.GeoHaystackSearch and MongoCollection.GeoHaystackSearchAs
+- MongoCollection.Group
+- MongoCollection.MapReduce (with MapReduceOutputMode.Inline)
+
+There is no helper method (yet) for the geoWalk command.