add doc deployment step

.github/workflows/install_and_test.yml

@@ -264,6 +264,39 @@ jobs:
         conda install -y -c conda-forge doxygen=1.9.5
         conda install -y  jinja2 pygments docutils
         ./build-public.sh
+    -name: deploy updated docs
+      run: |-
+        if [[ ${{ github.event_name }} == 'schedule' ]]; then
+          echo "Trigger: a nightly build. Deploying the docs."
+          git clone git@github.com:facebookmicrosites/habitat-website.git
+          cd habitat-website
+          git submodule update --init
+          for dir in habitat-sim habitat-lab
+          do
+              rm -rf published/docs/${dir}
+              cp -r ../habitat-sim/build/docs-public/${dir} published/docs/.
+          done
+
+          git config --global user.name "Habitat"
+          git config --global user.email habitat@fb.com
+          NOW=$(date +"%m-%d-%Y")
+          git add .
+          git diff-index --quiet HEAD || git commit -m "Build habitat-sim and habitat-lab ${NOW}"
+          git push origin main
+
+          # Deploy to public
+          git checkout gh-pages
+          git checkout main published
+          sudo apt-get update || true
+          sudo apt-get install -yq rsync
+          rsync -a published/ ./.
+          rm -rf published
+          git add .
+          git diff-index --quiet HEAD || git commit -m "Build habitat-sim and habitat-lab ${NOW}"
+          git push origin gh-pages
+        else
+          echo "Not a nightly build, no deployment needed."
+        fi
 
   build_conda_binaries:
     runs-on: 4-core-ubuntu-gpu-t4