Added add_footer details to README.md
Added add_footer details to README.md

yakovenkodenis/bullet,sho-h/brakefast,danp60/bullet,PikachuEXE/bullet,eileencodes/bullet,sideci-sample/sideci-sample-bullet,flyerhzm/bullet,hannahbot/bullet,rrosenblum/bullet,jay3126/bullet,rstacruz/bullet,dwb/bullet,yakovenkodenis/bullet,rstacruz/bullet,sho-h/brakefast,rrosenblum/bullet,flyerhzm/bullet,theass/bullet,PikachuEXE/bullet,hannahbot/bullet,sideci-sample/sideci-sample-bullet,eileencodes/bullet,theass/bullet,dwb/bullet,jay3126/bullet,danp60/bullet,flyerhzm/bullet