Repo: Remove mentions of the zulip (#2174)

Nobody's using it. Switch to github discussions instead.

Author: smalis-msft

CONTRIBUTE.MD

@@ -16,13 +16,5 @@ We strongly suggest asking for feedback before starting to work on a new feature
 functionality, etc. so that we can provide feedback and discuss how we can 
 collaborate on this and support contributors. 
 
-To engage with project maintainers, contributors can reach out on 
-[Zulip](https://openvmm.zulipchat.com/) and then start drafting a 
-[GitHub issue](https://github.com/microsoft/openvmm/issues/new?template=Blank+issue) 
-after getting some preliminary feedback on Zulip, or they can open a GitHub issue 
-to get preliminary feedback on GitHub and then reach out to us on Zulip to get 
-some more synchronous support. 
-
-We normally use Zulip for more informal conversations and GitHub Issues for more 
-formal, auditable, public discussion and progress tracking. We encourage contributors 
-to use both in either order based on preference.
+To engage with project maintainers, contributors can reach out through 
+[GitHub discussions](https://github.com/microsoft/openvmm/discussions).

SUPPORT.md

@@ -6,7 +6,7 @@ This project uses GitHub Issues to track bugs and feature requests. Please searc
 issues before filing new issues to avoid duplicates. For new issues, file your bug or 
 feature request as a new Issue.
 
-For help and questions about using this project, please reach out to us on [Zulip](https://openvmm.zulipchat.com/).
+For help and questions about using this project, please reach out to us through [Github discussions](https://github.com/microsoft/openvmm/discussions).
 
 ## Microsoft Support Policy