Merge pull request adafruit#61 from Spegs21/master

Add UF2 build/generation information to Readme

README.md

@@ -70,6 +70,20 @@ There is an adjacent ground pad.
 
 For other boards, please check the board definition for details.
 
+### Making your own UF2
+
+To create your own UF2 DFU update image, simply use the [Python conversion script](https://github.com/Microsoft/uf2/blob/master/utils/uf2conv.py) on a .bin file or .hex file, specifying the family as **0xADA52840**. Be sure to compile your application to start at 0x26000 (152k). If using a .bin file with the conversion script you must specify this with the -b switch.
+
+To create a UF2 image from a .bin file:
+```
+uf2conv.py firmware.bin -c -b 0x26000 -f 0xADA52840
+```
+
+To create a UF2 image from a .hex file:
+```
+uf2conv.py firmware.hex -c -f 0xADA52840
+```
+
 ## Burn & Upgrade with pre-built binaries
 
 You can burn and/or upgrade the bootloader with either a J-link or DFU (serial) to a specific pre-built binary version