periph/uart: add doc on low power implications
periph/uart: add doc on low power implications

josephnoir/RIOT,authmillenon/RIOT,x3ro/RIOT,miri64/RIOT,kYc0o/RIOT,mtausig/RIOT,jasonatran/RIOT,yogo1212/RIOT,josephnoir/RIOT,OTAkeys/RIOT,yogo1212/RIOT,ant9000/RIOT,RIOT-OS/RIOT,yogo1212/RIOT,kYc0o/RIOT,smlng/RIOT,miri64/RIOT,toonst/RIOT,authmillenon/RIOT,x3ro/RIOT,OlegHahm/RIOT,kaspar030/RIOT,OlegHahm/RIOT,jasonatran/RIOT,OlegHahm/RIOT,aeneby/RIOT,authmillenon/RIOT,josephnoir/RIOT,ant9000/RIOT,basilfx/RIOT,OlegHahm/RIOT,kaspar030/RIOT,authmillenon/RIOT,mtausig/RIOT,RIOT-OS/RIOT,jasonatran/RIOT,smlng/RIOT,miri64/RIOT,kaspar030/RIOT,kYc0o/RIOT,mtausig/RIOT,basilfx/RIOT,basilfx/RIOT,jasonatran/RIOT,OTAkeys/RIOT,josephnoir/RIOT,kYc0o/RIOT,OTAkeys/RIOT,authmillenon/RIOT,toonst/RIOT,mtausig/RIOT,toonst/RIOT,basilfx/RIOT,toonst/RIOT,OTAkeys/RIOT,smlng/RIOT,aeneby/RIOT,kaspar030/RIOT,aeneby/RIOT,ant9000/RIOT,mtausig/RIOT,jasonatran/RIOT,basilfx/RIOT,miri64/RIOT,kaspar030/RIOT,miri64/RIOT,aeneby/RIOT,toonst/RIOT,x3ro/RIOT,yogo1212/RIOT,aeneby/RIOT,RIOT-OS/RIOT,ant9000/RIOT,smlng/RIOT,RIOT-OS/RIOT,kYc0o/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,ant9000/RIOT,OlegHahm/RIOT,smlng/RIOT,authmillenon/RIOT,OTAkeys/RIOT,x3ro/RIOT,josephnoir/RIOT,x3ro/RIOT,yogo1212/RIOT