sys/evtimer: adjusted documentation for evtimer_on_ztimer
sys/evtimer: adjusted documentation for evtimer_on_ztimer

authmillenon/RIOT,kaspar030/RIOT,kaspar030/RIOT,ant9000/RIOT,miri64/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,ant9000/RIOT,OTAkeys/RIOT,ant9000/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,miri64/RIOT,authmillenon/RIOT,jasonatran/RIOT,OlegHahm/RIOT,jasonatran/RIOT,authmillenon/RIOT,OlegHahm/RIOT,kYc0o/RIOT,OTAkeys/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,kaspar030/RIOT,OTAkeys/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,ant9000/RIOT,kYc0o/RIOT,jasonatran/RIOT,authmillenon/RIOT,kYc0o/RIOT,miri64/RIOT,kYc0o/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,miri64/RIOT,jasonatran/RIOT,miri64/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,kaspar030/RIOT,ant9000/RIOT,authmillenon/RIOT,kaspar030/RIOT,RIOT-OS/RIOT