Change Zigbee name stylization from "ZigBee" to "Zigbee" in all docs and code

[Gamester17]

Documentation and code need to be updated to say "Zigbee" instead of "ZigBee" as the official Zigbee Alliance changed the Zigbee name stylization from “ZigBee” to “Zigbee”, as in they are no longer writing Zigbee with a capital “B” in the middle of the name.

[qm3ster]

Crazy how nature do that.
Next thing you know we'll all be speaking dotdot.

[Gamester17]

@qm3ster Not relevant as the dotdot standard will not replace Zigbee

https://www.zigbee.org/zigbee-for-developers/dotdot/