Add changelog & credits, update release notes

[jeffpaul]

What?

This pull request introduces documentation updates to improve clarity and accessibility for contributors and users. Key changes include the addition of a comprehensive changelog, a dedicated credits file, and enhancements to release and security documentation.

Documentation Updates:

Changelog:

• Added a new CHANGELOG.md file to document all notable changes in the project, adhering to the Keep a Changelog standard and Semantic Versioning. This provides a detailed history of updates, fixes, and features across versions.
• Updated readme.txt to include a summary of recent changes and a link to the full changelog for complete details.

Credits:

• Introduced a new CREDITS.md file listing maintainers, contributors, and libraries utilized in the project. This acknowledges the efforts of all individuals involved and improves transparency.
• Updated readme.md to link to the new CREDITS.md file for contributor recognition.

Release Process:

• Enhanced RELEASING.md with additional instructions for plugin committers, ensuring smoother release management and clarifying the committer requirements on wp.org.

Why?

Resolves the remaining, outstanding items in #544.

How?

Testing Instructions

Screenshots or screencast

Changelog Entry

Changed - Updated documentation.

[kasparsd]

This is great @jeffpaul, thanks for working on it! Had a few questions inline.

I know you have a lot of experience with the release workflows across many similar projects so I really appreciate your lead here!

[jeffpaul]

Note that along with @kasparsd review comments above that I'll update the PR with the latest release as well https://github.com/WordPress/two-factor/releases/tag/0.14.0

[masteradhoc]

@jeffpaul looks like a nice structure, do you think you could finalize this PR so its possible to merge it?

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

Unlinked Accounts

The following contributors have not linked their GitHub and WordPress.org accounts: @PluginVulnerabilities.

Contributors, please read how to link your accounts to ensure your work is properly credited in WordPress releases.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Unlinked contributors: PluginVulnerabilities.

Co-authored-by: jeffpaul <jeffpaul@git.wordpress.org>
Co-authored-by: kasparsd <kasparsd@git.wordpress.org>
Co-authored-by: masteradhoc <masteradhoc@git.wordpress.org>
Co-authored-by: iandunn <iandunn@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[jeffpaul]

@masteradhoc the changes here should now resolve @kasparsd concerns and be current with recent releases

[masteradhoc]

LGTM!

[kasparsd]

This is great!

@jeffpaul Do you have suggestions for how to automate this? For example, how did you generate the contributor list, or those links in the footer of the changelog?