README.md: adapt doc on tapsetup for new sudo requirement
README.md: adapt doc on tapsetup for new sudo requirement

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