chore: Add release instructions

Author: Techassi

rust/stackablectl/RELEASE.md

@@ -0,0 +1,15 @@
+# Release Process
+
+The release of `stackablectl` is currently mostly done manually. This means the following steps need
+to be done:
+
+1. Ensure your local `main` branch is up-to-date and then proceed to checkout a new branch using
+   `git checkout -b chore/release-stackablectl-X.Y.Z`.
+2. Update both the Cargo.toml and CHANGELOG.md file to the new version `X.Y.Z`.
+3. Update various files by running the following xtask `cargo xtask gen-man` and
+   `make regenerate-nix`. This is also automatically done if pre-commit is enabled.
+4. Push the changes and raise a PR.
+5. Merge the PR onto `main` and then proceed to tag the appropriate commit using
+   `git tag -s stackablectl-Y.Y.Z -m stackablectl-Y.Y.Z`.
+6. Building the artifacts and creating the release on GitHub is fully automated from this point
+   onward.