readme

README.md

 # cdn-node-checker
 
-Check CDN nodes and update AliDNS records.
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+Check CDN nodes and update AliDNS records.
+
+## How to use
+
+Build a Docker image from the given Dockerfile and run the container with `config.yaml` mounted on `/usr/src/app/config.yaml`.
+
+**Important: Make sure to use public DNS in the container.** You may want to use the `dns: 114.114.114.114` option in `docker-compose.yml` file.