properly handle reads up to 32 bytes

This gets the stop bit handling correct, after finding the -1 on count.

reads >32 bytes have a totally different command messge.
Add notes on inserting delays after the start bit

Tested at 20khz and 400khz with the logic analyser
trivial: include the length of the rx for easier verification
read 1-64 bytes ok, need to fix loops for >64