Delete link in HeartRateService.md

Delete broken link, so engine can build.

Author: Amanda Butler

docs/reference/api/connectivity/bluetooth/HeartRateService.md

@@ -10,8 +10,6 @@ The HeartRateService class implements the Bluetooth Heart Rate service as define
 
 ### HeartRateService class reference
 
-[![View code](https://www.mbed.com/embed/?type=library)](https://os-doc-builder.test.mbed.com/docs/v5.7/mbed-os-api-doxy/class_heart_rate_service.html)
-
 ### HeartRateService example
 
 [![View code](https://www.mbed.com/embed/?url=https://os.mbed.com/teams/mbed-os-examples/code/mbed-os-example-ble-HeartRate/)](https://os.mbed.com/teams/mbed-os-examples/code/mbed-os-example-ble-HeartRate/file/307bde0f868f/source/main.cpp)