Fix docs code style (#7937)

docs/watching-files.md

@@ -5,14 +5,16 @@ title: Watching For Changes
 
 If you prefer to have prettier watch for changes from the command line you can use a package like [onchange](https://www.npmjs.com/package/onchange). For example:
 
-```
+```bash
 npx onchange '**/*.js' -- npx prettier --write {{changed}}
 ```
 
 or add the following to your `package.json`
 
 ```json
+{
   "scripts": {
     "prettier-watch": "onchange '**/*.js' -- prettier --write {{changed}}"
-  },
+  }
+}
 ```