workflows: Add documentation workflow (#104)

.github/workflows/documentation.yml

@@ -0,0 +1,22 @@
+name: Documentation
+on:
+  push:
+    branches:
+      - master
+jobs:
+  documentation:
+    name: Documentation
+    runs-on: ubuntu-20.04
+    timeout-minutes: 30
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+        with:
+          persist-credentials: false
+      - name: Install dependencies
+        run: |
+          sudo apt update || true
+          sudo apt --yes --no-install-recommends install doxygen
+      - name: Generate documentation
+        run: |
+          doxygen