link to protobuf

README.md

@@ -1,6 +1,6 @@
 # Tinode Instant Messaging Server
 
-Instant messaging server. Backend in pure [Go](http://golang.org) (license [GPL 3.0](http://www.gnu.org/licenses/gpl-3.0.en.html)), custom client-side binding in Java and Javascript, as well as [gRPC](https://grpc.io/) client support for C++, C#, Go, Java, Node, PHP, Python, Ruby, Objective-C (license [Apache 2.0](http://www.apache.org/licenses/LICENSE-2.0)). Wire transport is JSON over websocket (long polling is also available) for custom bindings, or protobuf over plain TCP for gRPC. Persistent storage [RethinkDB](http://rethinkdb.com/), other databases can be supported by writing adapters.
+Instant messaging server. Backend in pure [Go](http://golang.org) (license [GPL 3.0](http://www.gnu.org/licenses/gpl-3.0.en.html)), custom client-side binding in Java and Javascript, as well as [gRPC](https://grpc.io/) client support for C++, C#, Go, Java, Node, PHP, Python, Ruby, Objective-C (license [Apache 2.0](http://www.apache.org/licenses/LICENSE-2.0)). Wire transport is JSON over websocket (long polling is also available) for custom bindings, or [protobuf](https://developers.google.com/protocol-buffers/) over plain TCP for gRPC. Persistent storage [RethinkDB](http://rethinkdb.com/), other databases can be supported by writing adapters.
 
 Tinode is meant as a replacement for XMPP. Overall it's a lot like open source WhatsApp or Telegram.