Add licenses to README.md

Change-Id: I7525184aeb9eb78d3dd1a91ac55ac88c6039afc6
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/151044
Tested-by: Trond Norbye <[email protected]>
Reviewed-by: Daniel Owen <[email protected]>

Author: trondn

README.md

@@ -23,6 +23,7 @@ Areas of interest in the repository:
       which interposes a real engine and can perform various types of
       error-injection.
 * `tests/` - Test cases.
+* `licenses/` - The various licenses in use
 
 ## Building