Add workflow to push README to Docker Hub (#108)

Author: lucacome

.github/workflows/dockerhub-description.yml

@@ -0,0 +1,25 @@
+name: Update Docker Hub Description
+on:
+  push:
+    branches:
+      - master
+    paths:
+      - README.md
+      - .github/workflows/dockerhub-description.yml
+jobs:
+  dockerHubDescription:
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Modify readme for DockerHub
+        run: |
+          sed -i '1,2d' README.md
+
+      - name: Docker Hub Description
+        uses: peter-evans/dockerhub-description@v2
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+          repository: nginx/nginx-ingress-operator
+          short-description: ${{ github.event.repository.description }}