add release checklist and changelog curation docs (#2598)

* add release checklist and changelog curation docs

* remove step for deleting '-dev' suffix from VERSION

docs/releases.md

@@ -0,0 +1,59 @@
+## Checklist
+
+Helix releases are versioned in the Calendar Versioning scheme:
+`YY.0M(.MICRO)`, for example `22.05` for May of 2022. In these instructions
+we'll use `<tag>` as a placeholder for the tag being published.
+
+* Merge the changelog PR
+* Tag and push
+    * `git tag -s -m "<tag>" -a <tag> && git push`
+    * Make sure to switch to master and pull first
+* Edit the `VERSION` file and change the date to the next planned release
+    * Releases are planned to happen every two months, so `22.05` would change to `22.07`
+* Wait for the Release CI to finish
+    * It will automatically turn the git tag into a GitHub release when it uploads artifacts
+* Edit the new release
+    * Use `<tag>` as the title
+    * Link to the changelog and release notes
+* Merge the release notes PR
+* Download the macos and linux binaries and update the `sha256`s in the [homebrew formula]
+    * Use `sha256sum` on the downloaded `.tar.xz` files to determine the hash
+* Link to the release notes in this-week-in-rust
+    * [Example PR](https://github.com/rust-lang/this-week-in-rust/pull/3300)
+* Post to reddit
+    * [Example post](https://www.reddit.com/r/rust/comments/uzp5ze/helix_editor_2205_released/)
+
+[homebrew formula]: https://github.com/helix-editor/homebrew-helix/blob/master/Formula/helix.rb
+
+## Changelog Curation
+
+The changelog is currently created manually by reading through commits in the
+log since the last release. GitHub's compare view is a nice way to approach
+this. For example when creating the 22.07 release notes, this compare link
+may be used
+
+```
+https://github.com/helix-editor/helix/compare/22.05...master
+```
+
+Either side of the triple-dot may be replaced with an exact revision, so if
+you wish to incrementally compile the changelog, you can tackle a weeks worth
+or so, record the revision where you stopped, and use that as a starting point
+next week:
+
+```
+https://github.com/helix-editor/helix/compare/7706a4a0d8b67b943c31d0c5f7b00d357b5d838d...master
+```
+
+A work-in-progress commit for a changelog might look like
+[this example](https://github.com/helix-editor/helix/commit/831adfd4c709ca16b248799bfef19698d5175e55).
+
+Not every PR or commit needs a blurb in the changelog. Each release section
+tends to have a blurb that links to a GitHub comparison between release
+versions for convenience:
+
+> As usual, the following is a summary of each of the changes since the last
+> release. For the full log, check out the git log.
+
+Typically, small changes like dependencies or documentation updates, refactors,
+or meta changes like GitHub Actions work are left out.