Update links in us_ticker.md

Avoid merge conflicts again because I changed links before merging this instead of after.

Author: Amanda Butler

docs/reference/contributing/target/us_ticker.md

@@ -48,7 +48,7 @@ We are working on the new HAL microsecond ticker API, which will replace the cur
 
 To make sure your platform is ready for the upcoming changes, you need to implement the future API and submit it in a separate pull request against the `feature-hal-spec-ticker` branch. You can find the API and specification for the new microsecond ticker API in the following header file:
 
-[![View code](https://www.mbed.com/embed/?type=library)](http://os.mbed.com/docs/development/feature-hal-spec-ticker-doxy/group__hal__us__ticker.html)
+[![View code](https://www.mbed.com/embed/?type=library)](http://os-doc-builder.test.mbed.com/docs/development/feature-hal-spec-ticker-doxy/group__hal__us__ticker.html)
 
 To enable microsecond ticker support in Mbed OS, add the `USTICKER` label in the `device_has` option of the target's section in the `targets.json` file.
 
@@ -62,8 +62,8 @@ mbed test -t <toolchain> -m <target> -n tests-mbed_hal-lp_us_ticker*,tests-mbed_
 
 You can read more about the test cases:
 
- [![View code](https://www.mbed.com/embed/?type=library)](http://os.mbed.com/docs/development/feature-hal-spec-ticker-doxy/group__hal__us__ticker.html)
+ [![View code](https://www.mbed.com/embed/?type=library)](http://os-doc-builder.test.mbed.com/docs/development/feature-hal-spec-ticker-doxy/group__hal__us__ticker.html)
 
- [![View code](https://www.mbed.com/embed/?type=library)](http://os.mbed.com/docs/development/feature-hal-spec-ticker-doxy/group__hal__ticker__tests.html)
+ [![View code](https://www.mbed.com/embed/?type=library)](http://os-doc-builder.test.mbed.com/docs/development/feature-hal-spec-ticker-doxy/group__hal__ticker__tests.html)
 
- [![View code](https://www.mbed.com/embed/?type=library)](http://os.mbed.com/docs/development/feature-hal-spec-ticker-doxy/group__hal__us__ticker__tests.html)
+ [![View code](https://www.mbed.com/embed/?type=library)](http://os-doc-builder.test.mbed.com/docs/development/feature-hal-spec-ticker-doxy/group__hal__us__ticker__tests.html)