docs(ci): add GitHub Actions section (#3558)

* docs: add link from README

* docs(ci): add GitHub Actions section

Author: knocte

README.md

@@ -160,6 +160,10 @@ A number of shared configurations are available to install and use with `commitl
 
 > ⚠️ If you want to publish your own shareable config then make sure it has a name aligning with the pattern `commitlint-config-emoji-log` or `commitlint-config-your-config-name` — then in extend all you have to write is `emoji-log` or `your-config-name`.
 
+## Documentation
+
+Check the [main website](https://commitlint.js.org/).
+
 ## API
 
 - Alternative, programmatic way to interact with `commitlint`

docs/guides-ci-setup.md

@@ -6,6 +6,47 @@ This guide assumes you have already configured `commitlint` for local usage.
 
 Follow the [Getting Started](./?id=getting-started) for basic installation and configuration instructions.
 
+## GitHub Actions
+
+An example of how a GitHub Actions workflow could validate the last commit message or all commit messages inside a Pull Request:
+
+```yml
+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  commitlint:
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install required dependencies
+        run: |
+          apt update
+          apt install -y sudo
+          sudo apt install -y git curl
+          curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash -
+          sudo DEBIAN_FRONTEND=noninteractive apt install -y nodejs
+      - name: Print versions
+        run: |
+          git --version
+          node --version
+          npm --version
+          npx commitlint --version
+      - name: Install commitlint
+        run: |
+          npm install conventional-changelog-conventionalcommits
+          npm install commitlint@latest
+
+      - name: Validate current commit (last commit) with commitlint
+        if: github.event_name == 'push'
+        run: npx commitlint --from HEAD~1 --to HEAD --verbose
+
+      - name: Validate PR commits with commitlint
+        if: github.event_name == 'pull_request'
+        run: npx commitlint --from ${{ github.event.pull_request.head.sha }}~${{ github.event.pull_request.commits }} --to ${{ github.event.pull_request.head.sha }} --verbose
+```
+
 ## Travis
 
 ```bash