Add command-line instructions to trigger deploy (#127)

Author: nicoddemus

RELEASING.rst

@@ -3,5 +3,8 @@ Here are the steps on how to make a new release.
 1. Create a ``release-VERSION`` branch from ``upstream/main``.
 2. Update ``CHANGELOG.rst``.
 3. Push the branch to ``upstream``.
-4. Once all tests pass, start the ``deploy`` workflow manually.
+4. Once all tests pass, start the ``deploy`` workflow manually, or execute::
+
+       gh workflow run deploy.yml -r release-VERSION -f version=VERSION
+
 5. Merge the PR.