lib : tinycrypt : Adding README for external library

Adding in a README file for the external library of TinyCrypt providing
details for origin, commit id, and where to find the original.

Source: Original to Zephyr Project

Change-Id: Ibc7ec33f7f459e8df88978b5b4505e67a2141998
Signed-off-by: Dan Kalowsky <daniel.kalowsky@intel.com>
1 file changed