Add new action

.github/workflows/doxygen.yml

@@ -0,0 +1,28 @@
+name: Doxygen
+description: 'Deploy the HTML pages generated by doxygen to GitHub pages'
+
+on:
+  push:
+    branches: [ 468-doc-automatically-deploy-the-doxygen-documents-to-github-pages ]
+  pull_request:
+    branches: [ 468-doc-automatically-deploy-the-doxygen-documents-to-github-pages ]
+
+env:
+  # Customize the CMake build type here (Release, Debug, RelWithDebInfo, etc.)
+  BUILD_TYPE: Release
+
+jobs:
+  using: "composite"
+
+  steps:
+  - uses: actions/checkout@v2
+
+  - name: Install Doxygen
+    run: sudo apt-get install doxygen graphviz -y
+    shell: bash
+
+  - name: Configure CMake
+    run: cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}} -Denable-doxygen-doc=ON
+
+  - name: Generate doxygen
+    run: cmake --build ${{github.workspace}}/build --config ${{env.BUILD_TYPE}} --target doc-html