add AvgPooling layer

mindspore/nn/layer/pooling.py

@@ -258,15 +258,6 @@ class AvgPool1d(_PoolNd):
         >>> output = pool(x)
         >>> output.shape()
         (1, 2, 4, 2)
-        >>> output
-        [[[[7.6640625 6.3320312]
-           [4.        4.3320312]
-           [5.3320312 3.6660156]
-           [7.3320312 7        ]]
-          [[5.6640625 5.6640625]
-           [6.3320312 5.3320312]
-           [3.6660156 5.6640625]
-           [5.3320312 5.3320312]]]]
     """
 
     def __init__(self,