Add `influx config -` command to CLI docs

Add command to switch to previous config

content/v2.0/reference/cli/influx/config/_index.md

@@ -30,6 +30,12 @@ influx config <config-name>
 influx config local-config
 ```
 
+To quickly switch back to the previous configuration, use the following command:
+
+```sh
+influx config -
+```
+
 ## Subcommands
 | Subcommand                                         | Description                              |
 |:----                                               |:-----------                              |