!49757 [docs] Update tensor document

Merge pull request !49757 from shaojunsong/code_docs_I6IYEU

docs/api/api_python/mindspore/mindspore.Tensor.rst

@@ -16,6 +16,9 @@ mindspore.Tensor
     输出：
         Tensor。
 
+    ..note::
+        `input_data` 的默认值None只作为一个占位符，并不意味着可以创建一个NoneType的Tensor。
+
 .. mscnautosummary::
     :toctree: Tensor
     :nosignatures:

mindspore/python/mindspore/common/tensor.py

@@ -104,6 +104,10 @@ class Tensor(Tensor_, metaclass=_TensorMeta):
     Outputs:
         Tensor.
 
+    Note:
+        The default value None of `input_data` works as a placeholder, it does not mean that we can create a NoneType
+        Tensor.
+
     Examples:
         >>> import numpy as np
         >>> import mindspore as ms