[COOK-1087] Update the CONTRIBUTING file to fix a minor typo
[COOK-1087] Update the CONTRIBUTING file to fix a minor typo

JasonGiedymin/dmg,juliandunn/dmg,opscode-cookbooks/dmg,turtlebender/dmg,thomasmeeus/dmg,clakeb/dmg,trinitronx/dmg,sax/dmg,JeanMertz/dmg,atlasdigital/dmg,Sauraus/dmg,cookbooks/oc-dmg,wenzowski/dmg,protec-cookbooks/dmg,chef-cookbooks/dmg,RoboticCheese/dmg,irabinovitch/dmg,cookbooks/hw-dmg,jeroenj/dmg,anonfunc/dmg