Fix typo in documentation
Fix typo in documentation

From Alex Yaremyuk (mutuh).

zzak/rake,envato/rake,ipmobiletech/rake,taiganakagawa/rake,88rabbit/rake,ruby/rake,tmornini/rake,jaustinhughey/rake,bentley/rake,hsbt/rake,pjump/rake,esasse/rake,hsbt/rake,ruby/rake,codedogfish/rake,utilum/rake,Vanzct/rake,askl56/rake,envato/rake