ml_dtypes: add documentation on how to release

RELEASING.md

@@ -0,0 +1,31 @@
+# Releasing ml_dtypes
+
+To create a new `ml_dtypes` release, take the following steps:
+
+1. Send a pull request updating the version in `pyproject.toml` and
+   `ml_dtypes/__init__.py` to the correct version number, as well as
+   updating `CHANGELOG.md` with the changes since the previous release
+   (an example for the 0.2.0 release is [PR #78]).
+2. Once this is merged, create the release tag and push it to github. An
+   example from the 0.2.0 release:
+   ```
+   $ git checkout main
+   $ git pull upstream main  # upstream is github.com:jax-ml/ml_dtypes.git
+   $ git log  # view commit log & ensure the most recent commit
+              # is your version update PR
+   $ git tag -a v0.2.0 -m "v0.2.0 Release"
+   $ git push upstream v0.2.0
+   ```
+3. Navigate to https://github.com/jax-ml/ml_dtypes/releases/new, and select
+   this new tag. Copy the change description from `CHANGELOG.md` into the
+   release notes, and click *Publish release*.
+4. Publishing the release will trigger the CI jobs configured in
+   `.github/workflows/wheels.yml`, which will build the wheels and source
+   distributions and publish them to PyPI. Navigate to
+   https://github.com/jax-ml/ml_dtypes/actions/workflows/wheels.yml and
+   look for the job associated with this release; monitor it to ensure it
+   finishes green (this will take approximately 30 minutes).
+5. Once the build is complete, check https://pypi.org/project/ml-dtypes/
+   to ensure that the new release is present.
+
+[PR #78]: https://github.com/jax-ml/ml_dtypes/pull/78