updated readme
updated readme

jesseract/slackbot_exercise_bot,ArcBees/slackbot-workout,freshbooks/slackbot-workout,jesseract/slackbot_exercise_bot,emillinden/slackbot-workout,brandonshin/slackbot-workout,Heyllow/slack-workout,TeachersPayTeachers/slackbot-workout,prlakhani/slackbot-workout,level3apps/Slackbot-workout,feighter09/exercise