Adds new renderer into the documentation

docs/api-guide/renderers.md

@@ -67,7 +67,7 @@ If your API includes views that can serve both regular webpages and API response
 
 ## JSONRenderer
 
-Renders the request data into `JSON`.
+Renders the request data into `JSON` enforcing ASCII encoding
 
 The client may additionally include an `'indent'` media type parameter, in which case the returned `JSON` will be indented.  For example `Accept: application/json; indent=4`.
 
@@ -75,6 +75,10 @@ The client may additionally include an `'indent'` media type parameter, in which
 
 **.format**: `'.json'`
 
+## UnicodeJSONRenderer
+
+Same as `JSONRenderer` but doesn't enforce ASCII encoding
+
 ## JSONPRenderer
 
 Renders the request data into `JSONP`.  The `JSONP` media type provides a mechanism of allowing cross-domain AJAX requests, by wrapping a `JSON` response in a javascript callback.