./script/trigger-release (#10589)

Add `./script/trigger-release {nightly|stable|preview}`

This command can be run regardless of the state of your local git
repository, and it
either triggers a workflow run of `bump_patch_version.yml` (for
stable/preview) or
it force pushes the nightly tag.

Also add some docs on releases to explain all of this.

Release Notes:

- N/A

docs/src/developing_zed__releases.md

@@ -0,0 +1,41 @@
+# Zed Releases
+
+Zed currently maintains two public releases for macOS:
+
+- [Stable](https://zed.dev/download). This is the primary version that people download and use.
+- [Preview](https://zed.dev/releases/preview), which receives updates a week ahead of stable for early adopters.
+
+Typically we cut a new minor release every Wednesday. The current Preview becomes Stable, and the new Preview contains everything on main up until that point.
+
+If bugs are found and fixed during the week, they may be cherry-picked into the release branches and so new patch versions for preview and stable can become available throughout the week.
+
+## Wednesday release process
+
+You will need write access to the Zed repository to do this:
+
+- Checkout `main` and ensure your working copy is clean.
+- Run `./script/bump-zed-minor-versions` and push the tags
+  and branches as instructed.
+- Wait for the builds to appear at https://github.com/zed-industries/zed/releases (typically takes around 30 minutes)
+- Copy the release notes from the previous Preview release(s) to the current Stable release.
+- Write new release notes for Preview. `/script/get-preview-channel-changes` can help with this, but you'll need to edit and format the output to make it good.
+- Download the artifacts for each release and test that you can run them locally.
+- Publish the releases.
+
+## Patch release process
+
+If your PR fixes a panic or a crash, you should cherry-pick it to the current stable and preview branches. If your PR fixes a regression in recently released code, you should cherry-pick it to the appropriate branch.
+
+You will need write access to the Zed repository to do this:
+
+- Cherry pick them onto the correct branch. You can either do this manually, or leave a comment of the form `/cherry-pick v0.XXX.x` on the PR, and the GitHub bot should do it for you.
+- Run `./script/trigger-release {preview|stable}`
+- Wait for the builds to appear at https://github.com/zed-industries/zed/releases (typically takes around 30 minutes)
+- Add release notes using the `Release notes:` section of each cherry-picked PR.
+- Download the artifacts for each release and test that you can run them locally.
+- Publish the release.
+
+## Nightly release process
+
+- Merge your changes to main
+- Run `./script/trigger-release {nightly}`