DOC: Update README adding "Usage" and "History" sections

README.md

@@ -3,3 +3,44 @@
 This GitHub composite action verifies that commit messages conform to the
 [Slicer commit style](https://slicer.readthedocs.io/en/latest/developer_guide/style_guide.html#commits)
 guidelines.
+
+## Usage
+
+To automatically enforce the Slicer commit message style during pull requests or
+pushes to the `main` branch, create a workflow file at
+`.github/workflows/check-commit-message.yml` with the following content:
+
+```yaml
+name: "Commit Message Check"
+on:
+  pull_request:
+    types:
+      - opened
+      - edited
+      - reopened
+      - synchronize
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+  pull-requests: read
+
+jobs:
+  check-commit-message:
+    name: Check Commit Message
+    uses: slicer/[email protected]
+    with:
+      token: ${{ secrets.GITHUB_TOKEN }}
+```
+
+This workflow will trigger commit message checks on relevant pull request events
+or when changes are pushed to the `main` branch.
+
+## History
+
+This action was originally implemented by
+[@jamesobutler](https://github.com/jamesobutler),
+[@pieper](https://github.com/pieper) and [@jcfr](https://github.com/jcfr) in the
+Slicer repository under `.github/workflows/commit-message.yml`.