Readme.md some issues

[Silveriomrs]

Good evening, Following some instructions about rotatory encoder, I have make 2 mistakes due to confuse info, perhaps it could be better to modify it, in order to make it more clear.

1. black text almost cannot be read.
2. Representation of rotatory encoder seems to be wrong.

For the first point, I suggest to do annotations with some kind of grey background or similar. Because they are written in the photos.

For the second... perhaps remove the circle from the symbol or a note make it clear which side of pins are referenced.

Thank you very much for your great work.