Update Conv3d descriptions

mindspore/nn/layer/conv.py

@@ -495,7 +495,7 @@ class Conv3d(_Conv):
 
     where :math:`ccor` is the cross-correlation operator.
 
-    If the 'pad_mode' is set to be "valid", the output height and width will be
+    If the 'pad_mode' is set to be "valid", the output depth, height and width will be
     :math:`\left \lfloor{1 + \frac{D_{in} + \text{padding[0]} + \text{padding[1]} - \text{kernel_size[0]} -
     (\text{kernel_size[0]} - 1) \times (\text{dilation[0]} - 1) }{\text{stride[0]}}} \right \rfloor` and
     :math:`\left \lfloor{1 + \frac{H_{in} + \text{padding[2]} + \text{padding[3]} - \text{kernel_size[1]} -