* Initial pass at insteon_plm documentation
* Amend transcription error
* Transcription error two
* Revise references to sensor_class to device_class
I just noticed PR # 5860 in hom-assistant is merged, so in anticipation of that
change I proactively updated this documentation to refer to device_class
instead of sensor_class in configuration examples.
* Oops! replace stale reference
* Revise customize: syntax to new (old) format
