$ref in ui schema

[gribakovs]

Hi, it would be worth to mention in the documentation that while using $ref in ui schema is not supported it is still possible to use it the same way it is used inside JSON Schema precompiling it with json-refs before handing over to JSON Forms.

E.g.:

....
"elements":[
{
"$ref":"URL"
}
]
........

[sdirix]

Good idea!