更新 README.md

[skip ci]

README.md

@@ -4,6 +4,7 @@
 ```bash
 docker rm -f gitea-runner-cache-server
 docker run -d --name gitea-runner-cache-server \
+  --label com.centurylinklabs.watchtower.enable=true \
   --restart unless-stopped \
   -e TZ=Asia/Shanghai \
   -v gitea-runner-cache-server:/runner-cache \