README.md: add news for pubsub changes
@@ -34,6 +34,15 @@ backwards-incompatible changes.
## News
+_March 17, 2017_
+
+Breaking Pubsub changes.
+* Publish is now asynchronous
+([announcement](https://groups.google.com/d/topic/google-api-go-announce/aaqRDIQ3rvU/discussion)).
+* Subscription.Pull replaced by Subscription.Receive, which takes a callback ([announcement](https://groups.google.com/d/topic/google-api-go-announce/8pt6oetAdKc/discussion)).
+* Message.Done replaced with Message.Ack and Message.Nack.
+
+
_February 14, 2017_
Release of a client library for Spanner. See
