Add manifest docs to messages errors bc it's not automatic
Add manifest docs to messages errors bc it's not automatic

Look, everyone! I'm taking one of @cvan's suggestions! Someone take
a screenshot!
mstriemer/app-validator,mozilla/app-validator,mozilla/app-validator,mstriemer/app-validator,mozilla/app-validator,diox/app-validator,eviljeff/app-validator,stasm/app-validator,diox/app-validator,stasm/app-validator,stasm/app-validator,diox/app-validator,mstriemer/app-validator,eviljeff/app-validator,mozilla/app-validator,diox/app-validator,stasm/app-validator,eviljeff/app-validator,eviljeff/app-validator