Remove community content from docs and point to zed.dev (#19895)

The community content now lives on zed.dev, discoverable via the navbar
`resources` menu.

See:

- https://github.com/zed-industries/zed.dev/pull/783

Release Notes:

- N/A

docs/src/SUMMARY.md

@@ -129,10 +129,3 @@
   - [Local Collaboration](./development/local-collaboration.md)
 - [Release Process](./development/releases.md)
 - [Debugging Crashes](./development/debugging-crashes.md)
-
-# Community
-
-- [Code of Conduct](./code-of-conduct.md)
-- [Contributing to Zed](./contribute-to-zed.md)
-- [Conversations](./conversations.md)
-- [Feedback and Support](./feedback-and-support.md)