add new pipeline for docu build

.github/workflows/documentation.yml

@@ -0,0 +1,29 @@
+name: Documentation
+on:
+  push:
+    paths-ignore:
+      - '**.md'
+      - '**.yml'
+      - '**.jpg'
+      - '**.jpeg'
+      - '**.png'
+      - '**.yaml'
+      - '**.json'
+jobs:
+  build_documentation:
+    runs-on: ubuntu-latest
+    # TODO Activate later: if: ${{ github.ref == 'refs/heads/main' }}
+    steps:
+      - name: Checkout the repository
+        uses: actions/checkout@v2
+        with:
+          ref: ${{ github.head_ref }}
+      - name: Install swag
+        run: go install github.com/swaggo/swag/cmd/swag@latest
+      - name: Install redoc
+        run: sudo apt install npm && sudo npm install redoc 
+      - name: Build the api documentation
+        run: swag init --parseDependency=true -d . -g cmd/pushbits/main.go
+      - name: Build static html
+        run: npx redoc-cli bundle docs/swagger.yaml --output index.html
+      # TODO copy index.html to new repo