gnrc_tftp: add deprecation note
gnrc_tftp: add deprecation note

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