.github: Add deploy action for gh-pages

This action will build the docs and deploy them to the `gh-pages` branch
on push to the `master` branch. Github Pages will pickup and host the
docs from the `gh-pages` branch.

Signed-off-by: Dylan Reimerink <[email protected]>

.github/workflows/deploy-gh-pages.yaml

@@ -0,0 +1,49 @@
+name: Deploy GH pages
+
+on:
+  push:
+    branches:
+      - master
+
+env:
+  USER: root
+
+jobs:
+  deploy-gh-pages:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Cache plugin data
+        id: cache-plugins
+        uses: actions/cache@v4
+        with:
+          path: .cache
+          key: cache-plugins
+      - name: Checkout gh-pages branch
+        run: |
+          git branch --delete --force gh-pages || true
+          git checkout -b gh-pages
+      - name: Apply deploy config
+        run: |
+          echo "" >> mkdocs.yml
+          echo "site_url: https://isovalent.github.io" >> mkdocs.yml
+          echo "" >> mkdocs.yml
+          echo "extra:" >> mkdocs.yml
+          echo "  analytics:" >> mkdocs.yml
+          echo "    provider: google" >> mkdocs.yml
+          echo "    property: G-KVJ1CK539N" >> mkdocs.yml
+      - name: Build html
+        run: |
+          make html PROD=true GH_TOKEN=${{ secrets.GITHUB_TOKEN }}
+          mv docs src
+          mv out docs
+      - name: Deploy to gh-pages
+        run: |
+          rm out/.gitignore || true
+          git config --global user.email "[email protected]"
+          git config --global user.name "GH Deploy Action"
+          git add -f docs/.
+          git commit -m "Deploy to gh-pages"
+          git push -f --set-upstream origin gh-pages
+
+