Fix instructions to rename windows executable
Fix instructions to rename windows executable

It should be called rack.exe, not rack

brint/rack,annegentle/rack,ryanvz/rack,jrperritt/rack,jrperritt/rack,dolph/rack,jarosser06/rack,nelsnelson/rack,brint/rack,rackspace/rack,ryanvz/rack,pratikmallya/rack,DonNateR/rack,rackspace/rack,pratikmallya/rack,jarosser06/rack,nelsnelson/rack,dolph/rack,annegentle/rack,DonNateR/rack