Migration path over from doudz/homeassistant-zigate

[ruimarinho]

Hi @doudz,

As a doudz/homeassistant-zigate user, I felt a bit lost on how to transition over to zigpy-zigate. I'd be happy to add this to the README.md once I get your help/feedback.

1. Stop HASS.
2. Remove custom_components/zigate and all configuration settings pertaining to zigate: .
3. Enable Zigbee integration by going into the Integrations panel on HASS frontend.

This is where I stopped. I got a timeout error which I had never seen before. Some comments on issues here and on the original project suggest erasing Zigate's and resetting the device.

It's also unclear what's the recommended unpairing/pairing strategy. Should I unpair all devices while still using doudz/homeassistant-zigate? Should zigate.remove_device be called at all?

Addtional insight from someone who has been through this transition would be very helpful to minimize mistakes.