Add notice to README about alternatives

Author: keegancsmith

README.md

@@ -1,5 +1,12 @@
 # Go Language Server [![Build Status](https://travis-ci.org/sourcegraph/go-langserver.svg)](https://travis-ci.org/sourcegraph/go-langserver)
 
+> *Note:* We have deprioritized work on this language server for use in
+> editors in favor of Google's upcoming Go language server. It is in the best
+> interests of the community to only have a single language server. If you
+> want to use a Go language server with your editor in the meantime, try
+> https://github.com/saibing/bingo, which is a partial fork of this repository
+> with fixes for Go modules and other editor bugs.
+
 go-langserver is a [Go](https://golang.org) language server that
 speaks
 [Language Server Protocol](https://github.com/Microsoft/language-server-protocol). It