Automate the changelog

[donnapep]

Is your feature request related to a problem? Please describe

We need to fully automate the changelog process in order to speed up deployments.

Goals

• [x] Write a post on Sensei P2 to kick off a discussion about the changelog format we should adopt going forward. This post should include:
  • How changelogs have historically been written. Here's an example.
  • The current output of the changelogger command (i.e. composer exec -- changelogger write).
  • Alternative formats we should consider adopting.
  • DONE - p6rkRX-64J-p2
• [x] Once a decision has been made about the format, implement the necessary changes to the changelogger tool. Important: The tool must not include issues / PRs in trunk that are behind a feature flag and have not yet shipped.

• [x] Introduce a way to update the Changelog section in readme.txt. From the Sensei LMS Release Process field guide page:

  Copy the new change log details to the Changelog section of readme.txt. Replace the log heading symbols: ### to #### and ## to ###. Only the last 3 releases should be displayed in this file, so remove the oldest entry if there are more than 3.

  DONE - https://github.com/Automattic/sensei/pull/6729

[donnapep]

@m1r0 I checked off the items that I think have already been completed. Is it correct that only the middle step is left?

[m1r0]

I think we're done with that one as well. We've decided to use the standard changelogger format and not change it. About the PRs behind a feature flag - we've decided not to add changelog entries to those PRs and just add one entry once the feature is ready. I don't think we can automate it any further. Or I'm missing something?

[donnapep]

@m1r0 Okey dokey.

we've decided not to add changelog entries to those PRs and just add one entry once the feature is ready

This bit seems worth calling out in the changelog entry best practices post. I'd already forgotten about it. 😅

[m1r0]

Yep, will do. Sounds like the Changelog Guidelines (p6rkRX-6dO-p2) flow chart is not a good approach. I will think of something... 😄