[cherry-pick] Polish en doc of LoDTensorArray, test=document_fix,...

[cherry-pick] Polish en doc of LoDTensorArray, test=document_fix, test=release/1.6 (#19972) (#20426)

paddle/fluid/API.spec

@@ -1087,7 +1087,7 @@ paddle.fluid.LoDTensor.recursive_sequence_lengths recursive_sequence_lengths(sel
 paddle.fluid.LoDTensor.set_lod set_lod(self: paddle.fluid.core_avx.LoDTensor, lod: List[List[int]]) -> None
 paddle.fluid.LoDTensor.set_recursive_sequence_lengths set_recursive_sequence_lengths(self: paddle.fluid.core_avx.LoDTensor, recursive_sequence_lengths: List[List[int]]) -> None
 paddle.fluid.LoDTensor.shape shape(self: paddle.fluid.core_avx.Tensor) -> List[int]
-paddle.fluid.LoDTensorArray ('paddle.fluid.core_avx.LoDTensorArray', ('document', 'e9895b67ba54438b9c0f7053e18966f5'))
+paddle.fluid.LoDTensorArray ('paddle.fluid.core_avx.LoDTensorArray', ('document', '54b28e608be8c035f2bbe18a5c12cfd2'))
 paddle.fluid.LoDTensorArray.__init__ __init__(self: paddle.fluid.core_avx.LoDTensorArray) -> None
 paddle.fluid.LoDTensorArray.append append(self: paddle.fluid.core_avx.LoDTensorArray, tensor: paddle.fluid.core_avx.LoDTensor) -> None
 paddle.fluid.CPUPlace ('paddle.fluid.core_avx.CPUPlace', ('document', 'd269ec68ce9b102ab10610e89ffa06e1'))

paddle/fluid/pybind/pybind.cc

@@ -1249,7 +1249,7 @@ All parameter, weight, gradient are variables in Paddle.
       });
 
   py::class_<LoDTensorArray>(m, "LoDTensorArray", R"DOC(
-    Array of LoDTensor.
+    LoDTensorArray is array of LoDTensor, it supports operator[], len() and for-loop iteration.
 
     Examples:
         .. code-block:: python
@@ -1279,6 +1279,12 @@ All parameter, weight, gradient are variables in Paddle.
            py::arg("tensor"), R"DOC(
              Append a LoDensor to LoDTensorArray.
               
+             Args:
+                   tensor (LoDTensor): The LoDTensor to be appended.
+
+             Returns:
+                   None.
+
              Examples:
                  .. code-block:: python