examples/gnrc_minimal: remove obsolete xbee reference from readme
examples/gnrc_minimal: remove obsolete xbee reference from readme

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