Build theme package on Github Action (#308)

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2e57a74..c974e8f 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -53,12 +53,12 @@
           echo "Here was the contents of the ./docs-archive directory" >> ./dist/docs/index.html
           find ./dist/
       - uses: actions/upload-artifact@v2
-        name: Upload documentation as artifact
+        name: Upload website as artifact
         if: ${{ github.event_name == 'pull_request' }}
         with:
           name: airflow-website
           path: './dist'
-      - name: Deploy documentation on asf-site branch
+      - name: Deploy website on asf-site branch
         uses: s0/git-publish-subdir-action@develop
         if: ${{ github.event_name == 'push' }}
         env:
@@ -66,3 +66,45 @@
           BRANCH: asf-site
           FOLDER: dist
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Copy files from site to theme
+        run: ./site.sh prepare-theme
+      - name: Prepare sphinx_airflow_theme package
+        working-directory: sphinx_airflow_theme
+        run: |
+          python3 -m pip install --user --upgrade setuptools wheel
+          python3 setup.py sdist bdist_wheel
+      - uses: actions/upload-artifact@v2
+        name: Upload sphinx_airflow_theme package as artifact
+        with:
+          name: airflow-sphinx-theme
+          path: './sphinx_airflow_theme/dist'
+      - name: Build theme demo
+        working-directory: sphinx_airflow_theme
+        run: |
+          pip install ./dist/sphinx_airflow_theme-*.whl
+          cd demo
+          ./docs.sh build
+      - uses: actions/upload-artifact@v2
+        name: Upload sphinx_airflow_theme demo as artifact
+        with:
+          name: airflow-sphinx-theme-demo
+          path: './sphinx_airflow_theme/demo/_build/html'
+      - name: Create releases on GitHub
+        working-directory: sphinx_airflow_theme
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          GITHUB_COMMIT: ${{ github.sha }}
+          GITHUB_REF: ${{ github.ref }}
+        if: >
+          github.ref == 'refs/heads/master' && github.repository == 'apache/airflow-site' &&
+          github.event_name == 'push'
+        run: |
+          gh auth status
+          gh release delete v0.0.1 -y || true
+          NOTES="Commit: ${GITHUB_COMMIT}
+          Source: ${GITHUB_REF}"
+
+          gh release create v0.0.1 \
+            --title "Latest version" \
+            --notes "${NOTES}" \
+            ./dist/*
diff --git a/sphinx_airflow_theme/README.md b/sphinx_airflow_theme/README.md
index bcd9562..f0f5535 100644
--- a/sphinx_airflow_theme/README.md
+++ b/sphinx_airflow_theme/README.md
@@ -20,25 +20,40 @@
 Sphinx theme for Airflow
 ========================
 
-Sphinx theme for Apache Airflow website.
+Sphinx theme for Apache Airflow documentation.
 
-# Getting started
+# Install from sources
 
 In order to start working with the theme, please follow the instructions below.
-1.  Make sure that your `python` shell command executes Python3 interpreter. If necessary, use a virtual environment:
 
-    `mkvirtualenv -p python3 <name_of_environment>`
+1.  Make sure your `python` shell command executes Python3 interpreter. If necessary, use a virtual environment:
+    ```
+    mkvirtualenv -p python3 <name_of_environment>
+    ```
 
 2.  To make Javascript and CSS code available for the theme, run the following command in the root directory:
-
-    `./site.sh build-site && ./site.sh prepare-theme`
+    ```
+    ./site.sh build-site && ./site.sh prepare-theme
+    ```
 
 3.  To install the required Python packages, in `<ROOT DIRECTORY>/sphinx_airflow_theme` run:
-
-    `pip install -e .`
+    ```
+    pip install -e .
+    ```
 
 4.  To launch the demo documentation page, in `<ROOT DIRECTORY>/sphinx_airflow_theme/demo` run:
-    `./docs.sh build && ./docs.sh preview`
+    ```
+    ./docs.sh build && ./docs.sh preview
+    ```
+
+# Install developer version
+
+To install the latest development version of a theme, run:
+```
+pip install 'https://github.com/apache/airflow-site/releases/download/v0.0.1/sphinx_airflow_theme-0.0.1-py3-none-any.whl'
+```
+Python packages for your PRs is available as downloadable artifact in GitHub Actions after
+the CI builds your PR.
 
 # Theme's source files
 
diff --git a/sphinx_airflow_theme/demo/awesome-cat.jpg b/sphinx_airflow_theme/demo/awesome-cat.jpg
index b2fce15..09f3e35 100644
--- a/sphinx_airflow_theme/demo/awesome-cat.jpg
+++ b/sphinx_airflow_theme/demo/awesome-cat.jpg
Binary files differ
diff --git a/sphinx_airflow_theme/setup.py b/sphinx_airflow_theme/setup.py
index c466748..09b7769 100644
--- a/sphinx_airflow_theme/setup.py
+++ b/sphinx_airflow_theme/setup.py
@@ -38,7 +38,7 @@
 
 setup(
     name='sphinx_airflow_theme',
-    version='0.0.01',
+    version='0.0.1',
     url='https://github.com/apache/airflow-site/tree/aip-11',
     license='Apache License 2.0',
     author='Apache Software Foundation',
@@ -51,6 +51,8 @@
     package_data={'sphinx_airflow_theme': [
         'theme.conf',
         '*.html',
+        'static/_gen/css/*.css',
+        'static/_gen/js/*.js',
         'static/css/*.css',
         'static/css/fonts/*.*'
         'static/js/*.js',