Move release process doc and update READMEs

[ciarams87]

Proposed changes

Problem: The release process doc contains information that is not relevant for NKG users, only for developers

Solution: Move the release documentation alongside the other developer documentation, and add versioning and release information relevant for an NKG user to the README

This commit also updates the docs README to include the missing monitoring doc reference.

Closes #896

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[bjee19]

What's the reason behind leaving the Versioning and Release Planning and Development sections in the docs/developer/release-process.md even after moving it to the higher level readme? I thought that the information for NKG users would be split and moved from the information for developers.

[kate-osborn]

There's also a link to the release process doc in the logging guidelines that needs to be updated: https://github.com/nginxinc/nginx-kubernetes-gateway/blob/main/docs/developer/logging-guidelines.md#evolution

[ciarams87]

What's the reason behind leaving the Versioning and Release Planning and Development sections in the docs/developer/release-process.md even after moving it to the higher level readme? I thought that the information for NKG users would be split and moved from the information for developers.

@bjee19 I think this information is still relevant for developers as well. Yes the same information will be in the README, but I think there's still value in keeping the sections co-lated in the dev guides.

[bjee19]

🚀