Modify the description for 3D of PoolLayer.

Author: kongsea

tensorlayer/layers.py

@@ -2906,7 +2906,7 @@ class PoolLayer(Layer):
     """
     The :class:`PoolLayer` class is a Pooling layer, you can choose
     ``tf.nn.max_pool`` and ``tf.nn.avg_pool`` for 2D or
-    ``tf.nn.max_pool3d()`` and ``tf.nn.avg_pool3d()`` for 3D.
+    ``tf.nn.max_pool3d`` and ``tf.nn.avg_pool3d`` for 3D.
 
     Parameters
     ----------