message: Add optional id information in README
diff: @@ -58,10 +58,14 @@ function logQuery(query) {
  `<QueryBuilder />` is the only top-level component exposed from this library. It supports the following properties:
  #### fields *(Required)*
  -[ {name:String, label:String} ]
  +[ {name:String, label:String, id:ID} ]
  The array of fields that should be used. Each field should be an object with
  -`{name:String, label:String}` |
  +
  +`{name:String, label:String, id:ID}` |
  +
  +The Id is optional, if you do not provide an id for a field then the name will be used
  +
  #### operators *(Optional)*
  [ {name:String, label:String} ]
  