docs: add self-hosting instruction

Author: JacobLinCool

README.md

@@ -22,9 +22,16 @@ LeetCode and LeetCode CN are both supported.
 
 It also has a [NPM package](https://www.npmjs.com/package/leetcode-card) and a [highly extensible system](./src/core/index.ts), so you can easily customize it to your needs.
 
-CLI tool will be created if I have time.
 Want to contribute? Feel free to open a pull request!
 
+## Self-hosting
+
+You can also self-host this service using the [`jacoblincool/leetcode-stats-card`](https://hub.docker.com/r/jacoblincool/leetcode-stats-card) Docker image.
+
+To build the image by yourself, use `pnpm build:image` script.
+
+See [docker-compose.yml](./docker-compose.yml) for an example.
+
 ## Usage
 
 Simply copy the code below, paste it into your `README.md`, and change the path to your leetcode username (case-insensitive).