Fix sphinx error

Author: kevin-brown

docs/conf.py

@@ -189,6 +189,8 @@
     ('py:class', 'rest_framework.exceptions.APIException'),
     ('py:class', 'rest_framework.serializers.Serializer'),
     ('py:class', 'rest_framework.renderers.BaseRenderer'),
+    ('py:class', 'rest_framework.renderers.JSONOpenAPIRenderer'),
+    ('py:class', 'rest_framework.renderers.OpenAPIRenderer'),
     ('py:class', 'rest_framework.parsers.BaseParser'),
     ('py:class', 'rest_framework.schemas.generators.EndpointEnumerator'),
     ('py:class', 'rest_framework.views.APIView'),