fixes some typos in README.md

Author: jiangkun1994

features/FEATURE_BLE/targets/TARGET_CORDIO/README.md

@@ -1,10 +1,10 @@
 # BLE API Cordio Implementation 
 
 The BLE API Cordio implementation allows Cordio licensee to easily deliver a 
-complete and up to date implementation of mbed BLE to their custommers using 
+complete and up to date implementation of mbed BLE to their customers using 
 mbed OS. 
 
-To deliver a BLE port, vendors simply have to provide an HCI driver taillored 
+To deliver a BLE port, vendors simply have to provide an HCI driver tailored 
 for the BLE module present on the board they want to support. 
 
 ## Source Organization