docs: add a link to the MCP channel on Discord (#35)

Author: jradcliff

README.md

@@ -4,6 +4,10 @@ This repo contains the source code for running a local
 [MCP](https://modelcontextprotocol.io) server that interacts with APIs for
 [Google Analytics](https://support.google.com/analytics).
 
+Join the discussion and ask questions in the
+[:robot:-analytics-mcp channel](https://discord.com/channels/971845904002871346/1398002598665257060)
+on Discord.
+
 ## Tools :hammer_and_wrench:
 
 The server uses the