CHANGES file: remove obsolete DSL notes and clarify incompatible DSL change
CHANGES file: remove obsolete DSL notes and clarify incompatible DSL change

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