added boards description

BOARDS.md

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+Boards with ESP-Link
+====================
+
+This readme provides instructions for PCBs that I've made that are designed for esp-link.
+Some of the instructions may be helpful to others as well.
+
+Installing esptool.py
+---------------------
+
+On Linux I am using [esptool.py](https://github.com/themadinventor/esptool) to flash the esp8266.
+If you're a little python challenged (like I am) then the following install instructions might help:
+ - Install ez_setup with the following two commands:
+   `wget https://bootstrap.pypa.io/ez_setup.py`
+	 `python ez_setup.py`
+	 I believe this will do something reasonable if you already have it (quite likely).
+ - Install esptool.py:
+   `git clone https://github.com/themadinventor/esptool.git`
+	 `python setup.py install`
+	 `cd ..`
+	 `esptool.py -h`
+
+Flashing esp-link
+-----------------
+
+Using esptool.py an esp-link release can be flashed as follows:
+```
+mkdir firmware
+cd firmware
+wget https://github.com/jeelabs/esp-link/releases/download/0.9.3/blank.bin
+wget https://github.com/jeelabs/esp-link/releases/download/0.9.3/boot_v1.3.b3.bin
+wget https://github.com/jeelabs/esp-link/releases/download/0.9.3/user1.bin
+esptool.py write_flash 0x00000 boot_v1.3.b3.bi 0x1000 user1.bin 0x7e000 blank.bin
+```
+(I see that I need to produce a tgz download...)
+
+esp-bridge
+----------
+
+The esp-bridge 
+
+