Delete release process docs (#41733)

These have been migrated to the README.md
[here](https://github.com/zed-industries/release_notes). These don't
need to be public. Putting them in the same repo where we draft
(`release_notes`) means less jumping around and allows us to include
additional information we might not want to make public.

Release Notes:

- N/A

docs/src/SUMMARY.md

@@ -165,6 +165,5 @@
   - [Local Collaboration](./development/local-collaboration.md)
   - [Using Debuggers](./development/debuggers.md)
   - [Glossary](./development/glossary.md)
-- [Release Process](./development/releases.md)
 - [Release Notes](./development/release-notes.md)
 - [Debugging Crashes](./development/debugging-crashes.md)