Add Discord url

Author: jdorfman

README.md

@@ -1,5 +1,5 @@
 # langserver.github.io
 
-Managed by [Sourcegraph](https://sourcegraph.com)
+Managed by [Sourcegraph](https://sourcegraph.com) · Join us on [Discord](https://srcgr.ph/discord-langserver-org).
 
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