1st attempt at Doxygen compiling on Actions

.github/workflows/doxygen.yml

@@ -31,12 +31,14 @@ jobs:
         working-directory: "." # default is .
 
     - name: Commit Doxygen HTML
-      if: ${{ false }}
+      if: github.event_name != 'pull_request'
+      env:
+        GH_DOXYGEN: ${{ secrets.GH_DOXYGEN }}
       run: |
         cd ..
         git clone https://github.com/speeduino/speeduino-doxygen
         cp -r speeduino/reference/doxygen/html/* speeduino-doxygen
         cd speeduino-doxygen
         git add --all
-        git commit --allow-empty -m "Deploy code docs to GitHub Pages. Travis build ${TRAVIS_BUILD_NUMBER}" -m "Commit ${TRAVIS_COMMIT}"
+        git commit --allow-empty -m "Deploy code docs to GitHub repo. Commit ${GITHUB_SHA}"
         git push --force "https://${GH_DOXYGEN}@github.com/speeduino/speeduino-doxygen" > /dev/null 2>&1