Update batchnorm documentation (number of outputs for training mode) (#…

…5932)

### Description
Update batchnorm documentation (number of outputs for training mode)

Redo of PR #5288 (since that PR is stalled).

---------

Signed-off-by: Ganesan Ramalingam <grama@microsoft.com>
Co-authored-by: Andreas Fehlner <fehlner@arcor.de>

docs/Changelog.md

@@ -19579,7 +19579,7 @@ This version of the operator has been available since version 15 of the default
 <dt><tt>momentum</tt> : float (default is 0.9)</dt>
 <dd>Factor used in computing the running mean and variance.e.g., running_mean = running_mean * momentum + mean * (1 - momentum).</dd>
 <dt><tt>training_mode</tt> : int (default is 0)</dt>
-<dd>If set to true, it indicates BatchNormalization is being used for training, and outputs 1, 2, 3, and 4 would be populated.</dd>
+<dd>If set to true, it indicates BatchNormalization is being used for training, and outputs 1 and 2 are to be computed.</dd>
 </dl>
 
 #### Inputs

docs/Operators.md

@@ -2439,7 +2439,7 @@ Other versions of this operator: <a href="Changelog.md#BatchNormalization-1">1</
 <dt><tt>momentum</tt> : float (default is 0.9)</dt>
 <dd>Factor used in computing the running mean and variance.e.g., running_mean = running_mean * momentum + mean * (1 - momentum).</dd>
 <dt><tt>training_mode</tt> : int (default is 0)</dt>
-<dd>If set to true, it indicates BatchNormalization is being used for training, and outputs 1, 2, 3, and 4 would be populated.</dd>
+<dd>If set to true, it indicates BatchNormalization is being used for training, and outputs 1 and 2 are to be computed.</dd>
 </dl>
 
 #### Inputs

onnx/defs/nn/defs.cc

@@ -1655,8 +1655,8 @@ ONNX_OPERATOR_SET_SCHEMA(
             0.9f)
         .Attr(
             "training_mode",
-            "If set to true, it indicates BatchNormalization is being used for training, and outputs 1, "
-            "2, 3, and 4 would be populated.",
+            "If set to true, it indicates BatchNormalization is being used for training, and outputs 1 "
+            "and 2 are to be computed.",
             AttributeProto::INT,
             static_cast<int64_t>(0))
         .Input(