Document release process

[rybak]

How creation of release draft works and creation of a GitHub release release works isn't obvious. I should document it.

Template's README has some of the details: https://github.com/JetBrains/intellij-platform-plugin-template#continuous-integration

[rybak]

Draft

1. Update pluginVersion in gradle.properties.
   • Sometimes the change is done before any commit for the release is ready (Maven style). Sometimes, it is created just before the release.
   • Examples:
     • d5935f0
     • 545da27
2. Push to GitHub the pluginVersion change and anything else that needs to be released
3. Wait for workflow "Build" to finish
4. Open the release draft created by the "Release Draft" step of the workflow
   • it is at the top of Releases
   • it is available in the build log of "Release Draft" step of workflow "Build"
5. Check the changelog in the draft
   • Fix typos in CHANGELOG.md, if any, and go back to step 2
6. Click button "Publish release"
7. Wait for workflow "Release" to finish
   • Workflow "Release" creates a changelog PR (example: CHANGELOG: 1.1.1 #6) and a tag (example: v1.1.1)
8. Check that the plugin got uploaded to the Marketplace
9. Fetch changelog PR locally – should be at the top of the PR list
10. Fast-forward merge changelog PR into the release branch (main)
11. Delete changelog branch
12. Mark GitHub Notifications for all of the above as "Done"