title: Django REST framework: method PUT not allowed in ViewSet with def update()
body: <p>In DRF, I have a simple ViewSet like this one:</p>
  
  <pre><code>class MyViewSet(viewsets.ViewSet):       
  
      def update(self, request):
          # do things...
          return Response(status=status.HTTP_200_OK)
  </code></pre>
  
  <p>When I try a PUT request, I get an error like method PUT not allowed. If I use <code>def put(self, request):</code> all things work fine. Accordingly to <a href="http://www.django-rest-framework.org/api-guide/viewsets/#marking-extra-actions-for-routing" rel="noreferrer">the docs</a> I should use <code>def update():</code> not <code>def put():</code>, why does it happen?</p>