Added 'shift+space = prev slide' to README.txt
Added 'shift+space = prev slide' to README.txt

puppetlabs/showoff,marrero984/showoff,puppetlabs/showoff,openminds/showoff-presentations,jiachenwang/showoff,slambert/showoff,wanix/showoff,binford2k/showoff,ivanoats/parade,technoweenie/showoff,pote/takeoff,burtlo/parade,rkh/showoff,binford2k/showoff,kublaj/showoff,nomadicoder/showoff,pote/takeoff,marrero984/showoff,nomadicoder/showoff,hybridgroup/showoff,nomadicoder/showoff,kublaj/showoff,nberger/showoff,guidance/nodejs-craft1933,jiachenwang/showoff,ivanoats/parade,openminds/showoff-presentations,marrero984/showoff,travisvalentine/7.27_showoff,binford2k/showoff,slambert/showoff,amiel/showoff,berkes/showoff,binford2k/showoff,puppetlabs/showoff,wanix/showoff,rkh/showoff,technoweenie/showoff,nomadicoder/showoff,karmajunkie/wtfomg,travisvalentine/7.27_showoff,jevy/Presentations,slambert/showoff,puppetlabs/showoff,jevy/Presentations,berkes/showoff,kublaj/showoff,amiel/showoff,berkes/showoff,slambert/showoff,pote/takeoff,marrero984/showoff,berkes/showoff,nberger/showoff,kublaj/showoff,hybridgroup/showoff,wanix/showoff,guidance/nodejs-craft1933,kublaj/showoff,burtlo/parade,karmajunkie/wtfomg,berkes/showoff,jiachenwang/showoff