update(README): more comments and guides, prettify the render of sub …

…command part and option part on Github.

README.md

@@ -6,24 +6,46 @@
 go install github.com/hduhelp/hdu-cli@latest
 ```
 
+<details>
+<summary>Trouble shoot</summary>
+
+> The Command may need root privilege
+>
+> and sometimes go env is not install completely on your root account
+>
+> so try like `sudo $GOROOT/bin/go install github.com/hduhelp/hdu-cli@latest`
+> 
+> By the way, if you follow the offical installation guide of GO, The goroot will be like /usr/local/go/
+</details>
+
 ## Usage
 
-### hdu-cli [command]
+### hdu-cli [sub command]
 
-### Available Commands:
+### Available Sub Commands:
 
-- completion  generate the autocompletion script for the specified shell
-- help        Help about any command
-- net         i-hdu network auth cli
+- completion  
+  - generate the autocompletion script for the specified shell
+- help        
+  - Help about any command
+- net         
+  - i-hdu network auth cli
 
 ### Flags:
 
-- --config string   config file (default is $HOME/.hdu-cli.yaml)
-- -h, --help            help for hdu_cli
-- -s, --save            save config
-- -V, --verbose         show more info
-- -v, --version         version for hdu_cli
+- --config string   
+  - config file (default is $HOME/.hdu-cli.yaml)
+  - more detail see comments at [hdu-cli.yaml example](./.hdu-cli.yaml)
+- -h, --help            
+  - help for hdu_cli
+- -s, --save            
+  - save config
+- -V, --verbose         
+  - show more info
+- -v, --version         
+  - version for hdu_cli
+
 
-Use "hdu_cli [command] --help" for more information about a command.
+Use `hdu_cli [sub command] --help` for more information about a command.