Happy Hare Warning

[garyd9]

More of a suggestion to update the Binky readme.md to mention that ERCF_CALIBRATE_ENCODER will likely generate a warning that can be ignored if using happy hare v1 software:

Warning: Encoder is not detecting the expected number of counts. It is possible that reflections from some teeth are unreliable

This can be worked around by editing the ercf.py file, but also seems safe to just ignore.