fix(CLI): 'about()' text for main commands
fix(CLI): 'about()' text for main commands

It shows up in the help, and makes it easier to navigate the command
tree without bringing up the html documentation.

Fixes #95
[skip ci]

steveklabnik/google-apis-rs,steveklabnik/google-apis-rs,steveklabnik/google-apis-rs,steveklabnik/google-apis-rs