Documentation: add uemd mb7707 barebox mini-howto

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Documentation/boards/uemd.rst

@@ -0,0 +1,40 @@
+UEMD
+====
+
+MB 77.07
+--------
+
+MB 77.07 board uses MBOOT as bootloader.
+MBOOT is a U-Boot clone with reduced functionality.
+See https://github.com/RC-MODULE/mboot for details.
+
+Running barebox
+^^^^^^^^^^^^^^^
+
+  1. Connect to the boards's UART (38400 8N1);
+
+  2. Turn board's power on;
+
+  3. Wait ``Hit any key (in 2 sec) to skip autoload...`` prompt and press the space key;
+
+  4. Compile ``zbarebox.bin`` image and upload it to the board via tftp
+
+.. code-block:: none
+
+  MBOOT # tftpboot zbarebox.bin
+  greth: greth_halt
+  TFTP Using GRETH_10/100 device
+  TFTP params: server 192.168.0.1 our_ip 192.168.0.7
+  TFTP params: filename 'zbarebox.bin' load_address 0x40100000
+  TFTP Loading: ################
+  TFTP done
+
+..
+
+  5. Run barebox
+
+.. code-block:: none
+
+  MBOOT # go 0x40100000
+
+..