Updated 'urls' (An array of API definition objects) description. (#4525)

* Updated 'urls' (An array of API definition objects) description.

Updated 'urls' (An array of API definition objects) description to show an actual object array containing two (2) urls, clarifying this configuration-option.

* urls is an array, not a string

docs/usage/configuration.md

@@ -30,7 +30,7 @@ Parameter Name | Description
 `domNode` | `Element`, **REQUIRED** if `dom_id` is not provided. The HTML DOM element inside which SwaggerUi will put the user interface for swagger. Overrides `dom_id`.
 `spec` | `Object={}`. A JS object describing the OpenAPI Specification. When used, the `url` parameter will not be parsed. This is useful for testing manually-generated specifications without hosting them.
 `url` | `String`. The url pointing to API definition (normally `swagger.json` or `swagger.yaml`). Will be ignored if `urls` or `spec` is used.
-`urls` | `String`. An array of API definition objects (`{url: "<url>", name: "<name>"}`) used by Topbar plugin. When used and Topbar plugin is enabled, the `url` parameter will not be parsed. Names and URLs must be unique among all items in this array, since they're used as identifiers.
+`urls` | `Array`. An array of API definition objects (`[{url: "<url1>", name: "<name1>"},{url: "<url2>", name: "<name2>"}]`) used by Topbar plugin. When used and Topbar plugin is enabled, the `url` parameter will not be parsed. Names and URLs must be unique among all items in this array, since they're used as identifiers.
 `urls.primaryName` | `String`. When using `urls`, you can use this subparameter. If the value matches the name of a spec provided in `urls`, that spec will be displayed when Swagger-UI loads, instead of defaulting to the first spec in `urls`.
 
 ##### Plugin system