docs: add harness-cli setup instructions

Author: xuyusong

README.md

@@ -19,6 +19,21 @@ Or initialize a new or existing repository with `harness-cli`:
 harness-cli init --language en
 ```
 
+You can also initialize a new or existing repository with [`harness-cli`](https://github.com/iFurySt/harness-cli).
+Install it from npm first:
+
+```sh
+npm install -g @ifuryst/harness-cli
+```
+
+Then run:
+
+```sh
+harness-cli init --language en
+```
+
+`harness-cli` requires Node.js 18+ and Go on your `PATH`.
+
 ## License
 
 [MIT](LICENSE)