Updated Appendix C: Firmware programming (markdown)

Appendix-C:-Firmware-programming.md

@@ -36,6 +36,8 @@ ICSP Pin 5 -> Arduino Pin D10   (RST/CS)
 ICSP Pin 6 -> Arduion GND       (GND)
 ```
 
+If your board doesn't have a header soldered to it (i.e. there are holes that go straight through the board instead of pins that jut out of the board), you'll need to ensure good physical contact between the wire and the pin holes in order for the programming step to work. See the Q&A at the bottom for more details.
+
 ## Step 3: Add the Ploopy Trackball board definition to the Arduino IDE
 In this step, you'll add the Ploopy Trackball board definition to your install of the Arduino IDE.