add DISCO_L475VG_IOT01A and remove K66F for ble examples

Author: Qinghao Shi

tools/test/examples/examples.json

@@ -76,7 +76,7 @@
             "BLE_Thermometer"
       ],
       "features" : ["BLE"],
-      "targets" : ["NRF51_DK", "NRF52_DK", "K66F", "NUCLEO_F401RE"],
+      "targets" : ["NRF51_DK", "NRF52_DK", "DISCO_L475VG_IOT01A"],
       "toolchains" : [],
       "exporters": [],
       "compile" : true,