update REAMDE for new structure usage

Signed-off-by: r4sas <r4sas@i2pmail.org>

README.md

@@ -0,0 +1,17 @@
+Prebuilt Boost libraries
+====
+
+Prebuilt Boost libraries for Android.
+
+Released so you don't have to spend a day messing around with scripts just in include Boost!
+
+*For list of available Boost versions check out repository [branches list](https://github.com/PurpleI2P/Boost-for-Android-Prebuilt/branches)!*
+
+Usage
+----
+
+To use built libraries clone required branch (as example, for boost 1.72.0):
+
+`git clone https://github.com/PurpleI2P/Boost-for-Android-Prebuilt.git -b boost-1_72_0`
+
+and configure your project to use cloned repository.