Adding notes about ARM processors

Compatible-Microcontrollers.md

@@ -1,4 +1,7 @@
-This runs on:
+# Atmel AVR
+
+QMK should run on any Atmel AVR processor with enough Flash. It has been tested on the following:
+
 * ATmega32U4 ([PJRC Teensy 2.0](http://www.pjrc.com/teensy/))
 * AT90USB1286 ([PJRC Teensy++ 2.0](http://www.pjrc.com/teensy/))
 * AT90USB1287 ([Atmel USBKEY](http://www.atmel.com/tools/AT90USBKEY.aspx))
@@ -10,4 +13,13 @@ This runs on:
 
 NOTE: To enable full features of firmware you'll need 32KB flash size.
 
-Please add any tested microcontrollers to this list.
+Please add any tested microcontrollers to this list.
+
+* ARM
+
+You can also use any ARM processor that ChibiOS supports. The following processors have been tested:
+
+* [Kinetis MKL26Z64](http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/kinetis-cortex-m-mcus/l-series-ultra-low-power-m0-plus/kinetis-kl2x-48-mhz-usb-ultra-low-power-microcontrollers-mcus-based-on-arm-cortex-m0-plus-core:KL2x)
+* [Kinetis MK20DX128](http://www.nxp.com/assets/documents/data/en/data-sheets/K20P64M50SF0.pdf)
+* [Kinetis MK20DX128](http://www.nxp.com/assets/documents/data/en/data-sheets/K20P64M50SF0.pdf)
+* [Kinetis MK20DX256](http://www.nxp.com/products/microcontrollers-and-processors/arm-processors/kinetis-cortex-m-mcus/k-series-performance-m4/k2x-usb/kinetis-k20-72-mhz-full-speed-usb-mixed-signal-integration-microcontrollers-mcus-based-on-arm-cortex-m4-core:K20_72)