Fixed couple of incorrect imports in the docs

docs/api-guide/reverse.md

@@ -28,7 +28,7 @@ Has the same behavior as [`django.core.urlresolvers.reverse`][reverse], except t
 You should **include the request as a keyword argument** to the function, for example:
 
     import datetime
-    from rest_framework.utils import reverse
+    from rest_framework.reverse import reverse
     from rest_framework.views import APIView
    
 	class APIRootView(APIView):

docs/api-guide/serializers.md

@@ -94,7 +94,7 @@ The `Serializer` class is itself a type of `Field`, and can be used to represent
 
 
     class CommentSerializer(serializers.Serializer):
-        user = serializers.UserSerializer()
+        user = UserSerializer()
         title = serializers.CharField()
         content = serializers.CharField(max_length=200)
         created = serializers.DateTimeField()