Add doxygen generation workflow on tag

.github/workflows/doxygen.yaml

@@ -0,0 +1,39 @@
+name: Build documentation
+
+on:
+  push:
+    tags: [ v* ]
+
+jobs:
+  build:
+    name: Build documentation
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          persist-credentials: false
+
+      - name: Get current tag
+        id: vars
+        run: echo ::set-output name=tag::${GITHUB_REF/refs\/tags\//}
+
+      - name: Set up Doxygen
+        run: sudo apt-get install -y doxygen
+
+      - name: Display Doxygen version
+        run: echo "Doxygen version $(doxygen -v)"
+
+      - name: Build documentation
+        run: |
+               cd nx
+               LIBNX_VERSION=${{ steps.vars.outputs.tag }} doxygen Doxyfile
+
+      - name: Deploy 🚀
+        uses: JamesIves/github-pages-deploy-action@3.7.1
+        with:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          BRANCH: gh-pages
+          FOLDER: nx/docs/html
+          CLEAN: true
+          SINGLE_COMMIT: true

.gitignore

@@ -7,6 +7,8 @@
 *.npdm
 *.pfs0
 Thumbs.db
+.*/
+!.github/
 debug/
 release/
 lib/

nx/Doxyfile

@@ -38,7 +38,7 @@ PROJECT_NAME           = "libnx"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = "$(TRAVIS_TAG)"
+PROJECT_NUMBER         = "$(LIBNX_VERSION)"
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a