New documentation for develop (#408)

* documentation refactoring

* documentation fixes

* distilled instructions for MDK

* remove deploy TODO after creating PR

* fixes typos

docs/boards/nrf52840dk.md

@@ -0,0 +1,50 @@
+# <img alt="OpenSK logo" src="../img/OpenSK.svg" width="200px">
+
+## Nordic nRF52840-DK board
+
+![Nordic development kit](../img/devkit_annotated.jpg)
+
+### Flashing using JTAG
+
+The development board comes with its own JTAG port, so the default programmer
+is the easiest and most convenient. You can flash OpenSK with these steps:
+
+1.  Connect a micro USB cable to the JTAG USB port.
+
+1.  Run our script for compiling/flashing Tock OS and OpenSK on your device:
+
+    ```shell
+    ./deploy.py --board=nrf52840dk_opensk --opensk
+    ```
+
+1.  Connect a micro USB cable to the device USB port.
+
+**Note**: Due to current limitations of our implementation and Tock, you may
+have to press the `BOOT/RESET` button, located next to the device USB port on
+the board in order to see your OpenSK device on your system.
+
+### Buttons and LEDs
+
+Out of the 5 buttons, the group of 4 behaves identically. They all convey user
+presence to the application. Some actions like register and login will make the
+board blink, asking you to confirm the transaction with a button press. The
+remaining fifth button restarts the board.
+
+The group of 4 LEDs on the right show the state of the app. There are different
+patterns:
+
+| Pattern                            | Cause                  |
+|------------------------------------|------------------------|
+| LED1 slow blink                    | kernel panic           |
+| all LEDs blinking together         | app panic              |
+| LED1+4 and LED2+3 fast alternating | asking for touch       |
+| fast swirling                      | wink (just saying Hi!) |
+| circle                             | allocator panic        |
+
+The LEDs closer to the JTAG port indicates the power and debugging state.
+
+There are 3 switches that need to be in the correct position:
+
+*   Power (bottom left): On
+*   nRF power source (center left): VDD
+*   SW6 (top right): DEFAULT