Update README for air help command

Author: xiantang

README.md

@@ -30,6 +30,16 @@ Note: This tool has nothing to do with hot-deploy for production.
 
 Support air config fields as arguments:
 
+You can view the available command-line arguments by running the following commands:  
+
+```
+air -h
+```
+or  
+```
+air --help
+```
+
 If you want to config build command and run command, you can use like the following command without the config file:
 
 ```shell