Update README on Docker Hub when docker is built

.github/workflows/docker.yml

@@ -82,6 +82,13 @@ jobs:
       - name: Image digest
         run: echo ${{ steps.docker_build.outputs.digest }}
 
+      - name: Update README
+        uses: peter-evans/dockerhub-description@v4
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_PASSWORD }}
+          repository: archivebox/archivebox
+       
       # This ugly bit is necessary if you don't want your cache to grow forever
       # until it hits GitHub's limit of 5GB.
       # Temp fix