Update Readme with known issues

[Kowitzki]

Firstly, thank you very much for your work. The pcbs work like a charm.
Could you update the readme with a known issues section?

• Like you said in your video: The ROW_EN and COL_EN lines need 10k pullup resistors to 5V, so the coils will not be harmed on a reset of the microcontroller.
• I had a little trouble with my 10x25 boards. Because the SENSE line is at row 16, and my board has no row 16, it could not autodetect its parameters. Rerouting the SENSE line to row 1 did the trick for me.

Maybe you could also add a link to your video series.