docs(): new ionic cli (#2326)

The package for the new ionic cli is `@ionic/cli`
Source:
https://ionicframework.com/blog/a-new-package-for-the-cli/

Author: brijmcq

docs/ionic/cli.md

@@ -13,7 +13,7 @@ npm uninstall -g ionic
 npm cache clean
 
 # reinstall clean version
-npm install -g ionic
+npm install -g @ionic/cli
 ```
 
 ### 1. Create a new project