docs: generate doxygen to gh-pages

.github/workflows/doxygen.yml

@@ -0,0 +1,22 @@
+name: Doxygen Genereate
+
+on:
+  push:
+    branches: [ main doxygen-test ]
+
+jobs:
+  doxygen:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: cachix/install-nix-action@v22
+      with:
+        github_access_token: ${{ secrets.GITHUB_TOKEN }}
+    - uses: actions/checkout@v3
+    - name: Build doxygen documentation
+      run: nix shell nixpkgs#doxygen nixpkgs#graphviz --command doxygen
+    - name: Deploy
+      uses: peaceiris/actions-gh-pages@v3
+      with:
+        github_token: ${{ secrets.GITHUB_TOKEN }}
+        publish_dir: ./html
+        force_orphan: true

.gitignore

@@ -1 +1,3 @@
 /build/
+
+/html/