fix(ci): remove broken doc links and improve release changelog format

Remove references to non-existent docs/guides/* files that produced
broken links in release notes. Replace with a single README.md
reference for installation and configuration guidance.

Add author attribution (by @username) to each changelog entry for
both tagged releases and nightly builds. Replace the static
"Thank you to all contributors!" message with a dynamically
generated contributor list written to CONTRIBUTORS.md and appended
to the release body.