Add section on BLE DFU for V2

docs/ble.rst

@@ -1,10 +1,13 @@
 Bluetooth
 *********
 
+micro:bit V1
+============
+
 While the BBC micro:bit has hardware capable of allowing the device to work as
 a Bluetooth Low Energy (BLE) device, it only has 16k of RAM. The BLE stack
 alone takes up 12k RAM which means there's not enough memory for MicroPython
-to support Bluetooth.
+to support Bluetooth on a micro:bit V1.
 
 .. note::
     MicroPython uses the radio hardware with the :mod:`radio` module. This
@@ -13,3 +16,15 @@ to support Bluetooth.
 
     Furthermore, the protocol used in the :mod:`radio` module is a lot simpler
     than BLE, making it far easier to use in an educational context.
+
+micro:bit V2
+============
+
+The nRF52833 used by the micro:bit V2 has 128k of RAM, allowing Micropython to make
+use of the BLE stack. Currently the only implemented feature is BLE flashing, allowing 
+a user to update the firmware on the micro:bit over Bluetooth.
+
+At the time that this was written the `Nordic DFU service <https://infocenter.nordicsemi.com/topic/sdk_nrf5_v16.0.0/lib_bootloader_dfu_process.html>`_ is implemented, and partial flashing is currently working but in
+beta. The Nordic DFU service updates everything in flash and will take a (relatively) long
+time to complete, whereas the partial flashing service only updates the filesystem containing
+the user scripts.