API RTOS documentation link improvement

[ReinhardKeil]

The doc link for OS Tick in
https://github.com/ARM-software/CMSIS_6/blob/main/ARM.CMSIS.pdsc#L434
could go to file:///C:/Users/reikei01/AppData/Local/Arm/Packs/ARM/CMSIS/6.1.0/CMSIS/Documentation/html/RTOS2/group__CMSIS__RTOS__TickAPI.html

Likewise the link for the RTOS2 header could go directly to the API section

[JonatanAntoni]

Fixed by #209