Update doxygen link to point to Power Management group

Author: bulislaw

docs/reference/api/platform/PowerManagement.md

@@ -46,7 +46,7 @@ These Mbed OS drivers can lock the deep sleep:
 
 ### Function reference
 
-[![View code](https://www.mbed.com/embed/?type=library)](http://os-doc-builder.test.mbed.com/docs/v5.7/mbed-os-api-doxy/mbed__sleep_8h_source.html)
+[![View code](https://www.mbed.com/embed/?type=library)](https://os-doc-builder.test.mbed.com/docs/development/mbed-os-api-doxy/group__platform__power__mgmt.html)
 
 ### Idle loop