Updated readme with note about pinout for Adafruit QtPy

Author: irl-ops

README.md

@@ -36,7 +36,7 @@ Set input clock divider and Turbo Mode (which uses a 96MHz instead of a 48Mhz in
 * For the Arduino Zero (untested), Adafruit Feather M0 (untested), and Adafruit Itsy Bitsy M0 you need to initialize timer 0 for pins 3, 4, 10 and 12, timer 1 for pins 8 and 9, and timer 2 for pins 11 and 13;
 * For the Arduino MKR series (untested), you need to initialize timer 1 for pins 2 and 3, timer 0 for pins 4, 5, 6 and 7, and timer 2 for pins 8 and 9;
 * For the Adafruit Trinket M0, you need to initialize timer 0 for pins 0 and 2, and timer 1 for pins 3 and 4.
-* For the Adafruit QtPy M0, you need to initialize timer 0 for pins 2, 3, 8, and 10. Timer 1 for pins 6, 7, and 9.  Timer 2 for pins 4 and 5.  
+* For the Adafruit QtPy M0, you need to initialize timer 0 for pins 2, 3, 8, and 10. Timer 1 for pins 6, 7, and 9.  Timer 2 for pins 4 and 5.  **Note** that pins 7 & 9 share a capture and compare buffer (CCB1) so you can't get different PWM waveforms from them at the same time.  
 
 MaxSteps is 0xFFFFFF for (24-bits) timers 0 and 1, and 0xFFFF for (16 bits) timer 2.