Merge pull request ARMmbed#109 from ranshe/patch-1

Updated readme.md

README.md

@@ -27,6 +27,7 @@ To build these examples, you need to have a computer with the following software
 In order to use BLE in mbed OS you need one of the following hardware combinations:
 
 * A Nordic nRF51-based board such as [nrf51dk](https://www.nordicsemi.com/eng/Products/nRF51-DK) or [mkit](https://www.nordicsemi.com/eng/Products/Bluetooth-R-low-energy/nRF51822-mKIT).
+* A Nordic nRF52-based board such as [nrf52DK](https://os.mbed.com/platforms/Nordic-nRF52-DK/)
 * A supported target, such as the [NUCLEO-F401RE](http://www.st.com/en/evaluation-tools/nucleo-f401re.html), with a BLE shield or an external BLE peripheral, such as an [ST shield](http://www.st.com/web/catalog/tools/FM116/SC1075/PF260517).
 * A [DISCO_L475VG_IOT01A (ref B-L475E-IOT01A)](http://www.st.com/en/evaluation-tools/b-l475e-iot01a.html) board.