Docs typo. Closes #2491.

docs/api-guide/parsers.md

@@ -128,7 +128,7 @@ If the view used with `FileUploadParser` is called with a `filename` URL keyword
         def put(self, request, filename, format=None):
             file_obj = request.data['file']
             # ...
-            # do some staff with uploaded file
+            # do some stuff with uploaded file
             # ...
             return Response(status=204)