update readme

Author: paul-szczepanek-arm

features/FEATURE_BLE/targets/TARGET_CORDIO/README.md

@@ -18,8 +18,7 @@ porting guide.
 implementation.
 * `sources`: BLE API Implementation files 
 * `stack`: Cordio stack 
-    * `cordio_stack`: Headerd of the cordio stack 
-    * `lib`: precompiled libraries of the cordio stack 
+    * `cordio_stack`: Headers and sources of the cordio stack 
     * `mbed_os_adaptation`: Headers of the interface responsible for the bridge
     between BLE API and the Cordio stack.