Feature Request: Improve documentation

Hi! First of all, thanks for the work!

I may be dumb but i don't find any documentation.

For example, what does "entities" part do in configutation...?

I tried to add a few entities, but nothing happened (?)

Also, what is the best practice to remove a configuration? I removed a test merged device, it broke everything, i can't find my original entities (but hey, there is an warning in your readme :) ) I removed it by first deselecting the devices to merge, and then remove the Device tools device.

Also, i saw that you have to reload the integration to apply modifications.