Merge pull request #7241 from will-am/fix_doc_paramattr

Fix doc of ParameterAttribute.

python/paddle/trainer_config_helpers/attrs.py

@@ -130,10 +130,12 @@ class ParameterAttribute(object):
     :param sparse_update: Enable sparse update for this parameter. It will
                           enable both local and remote sparse update.
     :type sparse_update: bool
+    :param update_hooks: A HookAttribute object.
+    :type update_hooks: HookAttribute
     :param initializer: If not None, it should be a callable object which accepts
                         a parameter name and returns numpy array for the initial
                         value of the parameter
-    :param initializer: callable object
+    :type initializer: callable object
     """
 
     def __init__(self,