periph/uart: fix line length in doc header
periph/uart: fix line length in doc header

rfuentess/RIOT,miri64/RIOT,kaspar030/RIOT,basilfx/RIOT,RIOT-OS/RIOT,josephnoir/RIOT,A-Paul/RIOT,miri64/RIOT,josephnoir/RIOT,BytesGalore/RIOT,yogo1212/RIOT,cladmi/RIOT,aeneby/RIOT,yogo1212/RIOT,jasonatran/RIOT,aeneby/RIOT,OlegHahm/RIOT,smlng/RIOT,lazytech-org/RIOT,kaspar030/RIOT,mfrey/RIOT,mfrey/RIOT,A-Paul/RIOT,RIOT-OS/RIOT,smlng/RIOT,basilfx/RIOT,A-Paul/RIOT,toonst/RIOT,kYc0o/RIOT,basilfx/RIOT,lazytech-org/RIOT,kaspar030/RIOT,yogo1212/RIOT,OlegHahm/RIOT,A-Paul/RIOT,mfrey/RIOT,lazytech-org/RIOT,BytesGalore/RIOT,lazytech-org/RIOT,basilfx/RIOT,OTAkeys/RIOT,jasonatran/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,aeneby/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,cladmi/RIOT,x3ro/RIOT,aeneby/RIOT,toonst/RIOT,yogo1212/RIOT,jasonatran/RIOT,jasonatran/RIOT,kYc0o/RIOT,OTAkeys/RIOT,basilfx/RIOT,josephnoir/RIOT,kYc0o/RIOT,smlng/RIOT,jasonatran/RIOT,gebart/RIOT,josephnoir/RIOT,authmillenon/RIOT,cladmi/RIOT,RIOT-OS/RIOT,mfrey/RIOT,x3ro/RIOT,RIOT-OS/RIOT,ant9000/RIOT,gebart/RIOT,mtausig/RIOT,x3ro/RIOT,authmillenon/RIOT,toonst/RIOT,miri64/RIOT,mtausig/RIOT,ant9000/RIOT,ant9000/RIOT,rfuentess/RIOT,kYc0o/RIOT,kYc0o/RIOT,gebart/RIOT,cladmi/RIOT,OlegHahm/RIOT,authmillenon/RIOT,authmillenon/RIOT,toonst/RIOT,ant9000/RIOT,rfuentess/RIOT,smlng/RIOT,mtausig/RIOT,aeneby/RIOT,miri64/RIOT,yogo1212/RIOT,OlegHahm/RIOT,kaspar030/RIOT,BytesGalore/RIOT,miri64/RIOT,mtausig/RIOT,x3ro/RIOT,ant9000/RIOT,cladmi/RIOT,lazytech-org/RIOT,authmillenon/RIOT,mtausig/RIOT,rfuentess/RIOT,toonst/RIOT,josephnoir/RIOT,RIOT-OS/RIOT,smlng/RIOT,gebart/RIOT,kaspar030/RIOT,gebart/RIOT,rfuentess/RIOT,BytesGalore/RIOT,A-Paul/RIOT,mfrey/RIOT,BytesGalore/RIOT,authmillenon/RIOT,x3ro/RIOT,yogo1212/RIOT