doc: update RELEASE.md and create release issue template (#78)

Closes #68

.github/issue_templates/release_template.md

@@ -0,0 +1,20 @@
+Before creating an issue with this template, 
+- replace `{{MAJOR_RELEASE}}` with the current major release, e.g., `v1`.
+- replace `{{SPECIFIC_RELEASE}}` with the specific release tag, e.g., `v1.0.0` or `v1.1.3`.
+- remove any todos that start with {{REMOVE IF NOT MAJOR RELEASE}} if this isn't a major release.
+
+# {{SPECIFIC_RELEASE}}
+- [ ] Create a `release/{{SPECIFIC_RELEASE}}` branch off of `main` for the release candidate.
+- Testing
+    - [ ] Run `functional_tests.yml` workflow on `release/{{SPECIFIC_RELEASE}}`.
+- [ ] Create a GitHub release of `release/{{SPECIFIC_RELEASE}}` with a `{{SPECIFIC_RELEASE}}` tag.
+    - [ ] Copy the release notes from the ## Unreleased section of CHANGELOG.md.
+- Git tag manipulation.
+    - [ ] Create a git tag named `{{SPECIFIC_RELEASE}}` pointing to the `release/{{SPECIFIC_RELEASE}}` branch
+    - [ ] {{REMOVE IF NOT MAJOR RELEASE}} Create a new git tag named `{{MAJOR_RELEASE}}`.
+    - [ ] Move the `{{MAJOR_RELEASE}}` tag to point to `release/{{SPECIFIC_RELEASE}}`.
+- [ ] Verify action with `uses: leanprover/lean-action@{{SPECIFIC_RELEASE}}` in test repo as a sanity check.
+- Create a PR to: 
+    - [ ] Create a PR to update CHANGELOG.md with the latest release.
+    - [ ] {{REMOVE IF NOT MAJOR RELEASE}} Update instances of `leanprover/lean-action@{{MAJOR_SPECIFIC_RELEASE}}` in README.md.
+- [ ] Post release announcement in `general/lean-action` Zulip topic.

RELEASING.md

@@ -10,10 +10,15 @@ A major version tag is maintained for each version which points to the latest ve
 
 For more information about releasing GitHub actions see the [Using tags for release management](https://docs.github.com/en/actions/creating-actions/about-custom-actions#using-tags-for-release-management) section of the GitHub custom actions documentation.
 
-## Steps to create a release
-- Create an issue to track creating the release.
+## Creating a release
+To create a release create an issue title `{RELEASE_VERSION} release`
+with the `.github/issue_templates/release_template.md` template
+and the `release` GitHug issue label.
+Follow the steps in the issue template.
+
+Here is an outline of the release process. There are more details in the release issue template.
 - Create a `release/v{RELEASE_VERSION}` branch (e.g. `release/v2.7.1`).
-    - Test `lean-action` by pointing an existing test repository to the new version with `uses: leanprover/lean-action@v{RELEASE_VERSION}`.
+    - Run the `functional_test.yml` workflow on `release/lean-action@v{RELEASE_VERSION}`.
     - Make any minor commits related to the release on the release branch.
 - Once the release has been validated, create a new release with release notes copied from the `## Unreleased` section of `CHANGELOG.md` and a git tag `v{RELEASE_VERSION}` (e.g `v2.7.1`).
 - In the case of a minor or patch version, move the major version tag to the latest version