Update README.md

remove mention of IRC.

README.md

@@ -21,10 +21,7 @@ If you find this happening to you, please check that you have followed the
 [getting started instructions](https://input-output-hk.github.io/haskell.nix/tutorials/getting-started#setting-up-the-binary-cache) and
 consult the corresponding [troubleshooting section](https://input-output-hk.github.io/haskell.nix/troubleshooting#why-am-i-building-ghc).
 
-The troubleshooting documentation also contains some help for other common issues.
-Please give it a read before asking on IRC or opening an issue.
-
-If you're still stuck, join the [#haskell.nix](https://www.irccloud.com/invite?channel=%23haskell.nix&hostname=irc.libera.chat&port=6697&ssl=1) channel on [irc.libera.chat](https://libera.chat/), or open an issue.
+The troubleshooting documentation also contains some help for other common issues. If you're still stuck open an issue.
 
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