Fix list_all_files docstring

kittengroomer/helpers.py

@@ -283,7 +283,7 @@ class KittenGroomerBase(object):
             return False
 
     def _list_all_files(self, directory):
-        """Generate an iterator over all the files in a directory tree."""
+        """Generator yield path to all of the files in a directory tree."""
         for root, dirs, files in os.walk(directory):
             for filename in files:
                 filepath = os.path.join(root, filename)