Add git tag -a to release process (#356)

The GitHub Releases feature creates lightweight tags, not annotated tags.

RELEASE_PROCESS.md

@@ -9,6 +9,8 @@
     - [`maud_macros`](maud_macros/src/lib.rs)
 4. `cd docs && cargo update`
 5. Commit to a new branch `release-X.Y.Z`, open a PR, fix issues, merge
-6. [Create a release](https://github.com/lambda-fairy/maud/releases/new)
-7. [Verify that documentation was published](https://github.com/lambda-fairy/maud/actions?query=workflow%3A%22Publish+docs%22) (this should have been triggered by the release)
-8. `cargo publish`
+6. `git tag -a vX.Y.Z && git push --tags`
+    - For the description, use a [My Little Pony quote](https://mlp.fandom.com/wiki/Maud_Pie#Quotes)
+7. [Create a release](https://github.com/lambda-fairy/maud/releases/new) against the new tag
+8. [Verify that documentation was published](https://github.com/lambda-fairy/maud/actions?query=workflow%3A%22Publish+docs%22) (this should have been triggered by the release)
+9. `cargo publish`