Fix minor typos.

Mardkown links syntax was inverted :)

CONTRIBUTING.md

@@ -1,7 +1,7 @@
 # Hello!
 We are an open source project of [ARM mbed](https://www.mbed.com). Contributions via [pull request](https://github.com/ARMmbed/ble/pulls), and [bug reports](https://github.com/ARMmbed/ble/issues) are welcome!
 
-Please submit your pull request to the 'develop' branch of this module. Commits to develop will merge into master at the time of the next release.
+Please submit your pull request to the `develop` branch of [this module](https://github.com/ARMmbed/ble/tree/develop). Commits to develop will be merge into the master branch at the time of the next release.
 
 # Contributor agreement
 For your pull request to be accepted, we will need you to agree to our [contributor agreement](https://developer.mbed.org/contributor_agreement/) to give us the necessary rights to use and distribute your contributions. (To click through the agreement create an account on mbed.com and log in.)

DOXYGEN_FRONTPAGE.md

@@ -1,16 +1,15 @@
 #BLE API
 
-The BLE module within mbed OS offers a high level abstraction for using
+The BLE module within mbed OS offers a high abstraction level for using
 Bluetooth Low Energy on multiple platforms.
 
-This documentation describes the internal structure of mbed
-(BLE_API)[https://github.com/armmbed/ble]. It was automatically generated from
-specially formatted comment blocks in BLE_API's source code using Doxygen.
-(See http://www.stack.nl/~dimitri/doxygen/ for more information on Doxygen).
+This documentation describes the internal structure of the mbed
+[BLE API](https://github.com/armmbed/ble). It was automatically generated from
+specially formatted comment blocks in BLE API's source code using Doxygen (see http://www.stack.nl/~dimitri/doxygen/ for more information on Doxygen).
 
-For getting started with BLE on mbed, check our (introduction
-page)[https://docs.mbed.com/docs/ble-intros/en/latest/].
+For getting started with BLE on mbed, check our [introduction
+page](https://docs.mbed.com/docs/ble-intros/en/latest/).
 
-For mbed OS examples using BLE, check (this
-repository)[https://github.com/armmbed/ble-examples]. For mbed-classic
-examples, refer to (code under mbed.org)[https://developer.mbed.org/teams/Bluetooth-Low-Energy/code/].
+For mbed OS examples using BLE, check [this
+repository](https://github.com/armmbed/ble-examples). For mbed-classic
+examples, please refer to [code under mbed.org](https://developer.mbed.org/teams/Bluetooth-Low-Energy/code/).