pkg/tweetnacl: remove trailing whitespaces from doc.txt
pkg/tweetnacl: remove trailing whitespaces from doc.txt

kYc0o/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,miri64/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,ant9000/RIOT,jasonatran/RIOT,authmillenon/RIOT,kYc0o/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,authmillenon/RIOT,OTAkeys/RIOT,kYc0o/RIOT,miri64/RIOT,kYc0o/RIOT,ant9000/RIOT,jasonatran/RIOT,OlegHahm/RIOT,RIOT-OS/RIOT,miri64/RIOT,ant9000/RIOT,kaspar030/RIOT,authmillenon/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,jasonatran/RIOT,OlegHahm/RIOT,miri64/RIOT,authmillenon/RIOT,jasonatran/RIOT,authmillenon/RIOT,kaspar030/RIOT,kaspar030/RIOT,miri64/RIOT,OlegHahm/RIOT,kYc0o/RIOT,jasonatran/RIOT,ant9000/RIOT,kaspar030/RIOT,ant9000/RIOT