Add readme for ee/lib/remote_development

Issue: Add remote development issue and MR templates (#415493 - closed)

What does this MR do and why?

See Add remote development issue and MR templates (#415493 - closed) for details.

See rendered version of page here: https://gitlab.com/gitlab-org/gitlab/-/blob/caw-rd-readme/ee/lib/remote_development/README.md

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.