checkboxradio property label presented in api document

[GaryG]

In documentation label option is clearly presented and described ​http://api.jqueryui.com/checkboxradio/#option-label

But based on bug #15138 a conclusion can be made that label option is not supported and is not considered as a feature.

Which in itself is weird because in old code commits such feature can be seen at least partially implemented. ​https://github.com/jquery/jquery-ui/commit/d903e1aa14e884d4d45fb1effeecd97d9e231fd2

Label option should be removed from documentation or option implemented.