Add improved instructions to the Todo list

[joewalch]

I've been using a variety of homebridge plugins using the HOOBS platform for a while and this plug in is different in that it doesn't explain itself very well to the user.

A couple of things I've noticed so far:

No explanation on what format to add excluded devices
Warning that imncomplete config will result in homebridge refusing to start.

I'm happy to help add some plain English to the Details if needed.