add help suggestions for the client

[kolharsam]

On the feature tracker here: https://github.com/kolharsam/goki#feature-tracker

This issue tracks the 4th one on the list.

What needs to be done?

So, on the client, users can get pass a wrong command, like st for set or got for get, in such cases we can show information like what git or npm do.
Like so:

                      Did you mean any of these commands?
                          - set

If it's an unknown command altogether, then show a list of all currently supported commands!