Update buidlroot to version 2016.08.1

bsp/buildroot/board/boundarydevices/common/readme.txt

@@ -0,0 +1,30 @@
+Buildroot for Boundary Devices platforms:
+
+https://boundarydevices.com/product-category/popular-sbc-and-som-modules/
+
+Here is the list of targeted platforms per defconfig:
+
+- nitrogen6x_defconfig
+  - BD-SL-i.MX6 (SABRE-Lite)
+  - Nitrogen6X
+  - Nitrogen6_Lite
+  - Nitrogen6_MAX
+  - Nitrogen6_VM
+  - Nitrogen6_SOM
+  - Nitrogen6_SOMv2
+
+- nitrogen6sx_defconfig
+  - Nitrogen6_SoloX
+
+- nitrogen7_defconfig
+  - Nitrogen7
+
+To install, simply copy the image to a uSD card:
+
+$ sudo dd if=output/images/sdcard.img of=/dev/sdX
+
+Where 'sdX' is the device node of the uSD partition.
+
+To upgrade u-boot, cancel autoboot and type:
+
+> run upgradeu