* Add missing `unique_id` part to Switch MQTT docs
`unique_id` is referenced within the doc, but isn't documented. I've copied the text from `Climate`.
* Remove references to HVAC
I was surprised that I cannot define the Id of the created switch, it is difficult to use it in automation without an id. It turns out that there is `unique_id` parameter, so why not show it to the world?
* add notes about payload_xxx, state_xxx and value_template
There is a complex relationship between payload_xxx, state_xxx and value_template but it’s not reflected at all or well enough to understand how to use them.
That leads to a lot of confusion on how to configure it properly (like this- https://community.home-assistant.io/t/mqtt-switch-value-template/175463)
I think my notes will help.
* ✏️ Tweak
Co-authored-by: Klaas Schoute <klaas_schoute@hotmail.com>
