debug doc typo

Hi, This is a bit more of a typo report.

In the Debug Logger doc page, app_trace_init() is supposed to return an int but in its function declaration it's said to return void.

Also, if someone has a simple suggestion to use it without keil's microlib I could be interested ;) (with newlib?)

Cheers, Cedric.

PS: the typo is also in the doc of debug.h and debug_init() in the previous versions