Add releasing instructions to the README

Author: asmeurer

README.md

@@ -300,3 +300,54 @@ corresponding document does not yet exist for PyTorch, but you can examine the
 various comments in the
 [implementation](https://github.com/data-apis/array-api-compat/blob/main/array_api_compat/torch/_aliases.py)
 to see what functions and behaviors have been wrapped.
+
+
+## Releasing
+
+To release, first note that CuPy must be tested manually (it isn't tested on
+CI). Use the script
+
+```
+./test_cupy.sh
+```
+
+on a machine with a CUDA GPU.
+
+Once you are ready to release, create a PR with a release branch, so that you
+can verify that CI is passing. You must edit
+
+```
+array_api_compat/__init__.py
+```
+
+and update the version (the version is not computed from the tag because that
+would break vendorability). You should also edit
+
+```
+CHANGELOG.md
+```
+
+with the changes for the release.
+
+Then create a tag
+
+```
+git tag -a <version>
+```
+
+and push it to GitHub
+
+```
+git push origin <version>
+```
+
+Check that the `publish distributions` action works. Note that this action
+will run even if the other CI fails, so you must make sure that CI is passing
+*before* tagging.
+
+This does mean you can ignore CI failures, but ideally you should fix any
+failures or update the `*-xfails.txt` files before tagging, so that CI and the
+cupy tests pass. Otherwise it will be hard to tell what things are breaking in
+the future. It's also a good idea to remove any xpasses from those files (but
+be aware that some xfails are from flaky failures, so unless you know the
+underlying issue has been fixed, a xpass test is probably still xfail).