message: Update the doc.
diff: </dl>
  +* **Constant**
  +
  + A constant tensor.
  + * **attribute**:
  + <dl>
  + <dt>value</dt>
  + <dd>The value for the elements of the output tensor.</dd>
  + </dl>
  + * **input**:
  + * **output**:
  + <dl>
  + <dt>output</dt>
  + <dd>Output tensor containing the same value of the provided tensor.</dd>
  + </dl>
  +
  +
  * **Conv**
  The convolution operator consumes an input tensor and a filter, and
  <dt>strides</dt>
  <dd>stride along each axis.</dd>
  </dl>
  - * **input**:
  + * **input**:2 - 3
  <dl>
  <dt>X</dt>
  <dd>Input data tensor from previous layer; has size (N x C x H x W), where N is the batch size, C is the number of channels, and H and W are the height and width. Note that this is for the 2D image.Otherwise the size is (N x D1 x D2 ... x Dn)</dd>
  