Remove reference to `addons:resources` command

What it says on the tin. Less confusion :tada: 
I think this is the resource code on a failed create (422) representing invalid params on the requested add-on. I could argue that 404 might be more appropriate, but could also re-argue 422. Anyway, it is 422 presently and due to the nature of calling here via CLI it is probably pretty safe to say a 422 means a wrong addon name instead of something else (I suspect there may be edge cases, so checking the body for error details might be safest).