.github: generate documentation using mkdocs

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

.github/workflows/docs.yml

@@ -0,0 +1,65 @@
+name: Dotty the Documenteer
+
+on:
+  push:
+    paths:
+      - 'doc/**'
+      - 'README.md'
+      - 'mkdocs.yml'
+      - '.github/workflows/docs.yml'
+  pull_request:
+    paths:
+      - 'doc/**'
+      - 'README.md'
+      - 'mkdocs.yml'
+      - '.github/workflows/docs.yml'
+
+permissions:
+  contents: read
+  pages: write
+  id-token: write
+
+concurrency:
+  group: "pages"
+  cancel-in-progress: false
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0  # Needed for git-revision-date-localized plugin
+
+      - name: Setup Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: '3.x'
+
+      - name: Install dependencies
+        run: |
+          pipx install mkdocs
+          pipx inject mkdocs mkdocs-material
+          pipx inject mkdocs pymdown-extensions
+          pipx inject mkdocs mkdocs-callouts
+
+      - name: Build documentation
+        run: mkdocs build
+
+      - name: Upload Pages artifact
+        uses: actions/upload-pages-artifact@v3
+        with:
+          path: site/
+
+  deploy:
+    if: github.ref == 'refs/heads/master' && github.event_name == 'push'
+    needs: build
+    runs-on: ubuntu-latest
+    environment:
+      name: github-pages
+      url: ${{ steps.deployment.outputs.page_url }}
+    steps:
+      - name: Deploy to GitHub Pages
+        id: deployment
+        uses: actions/deploy-pages@v4