[SCU][Add API Legend No.21] Add the legend of scatter_nd_add_cn

docs/api/paddle/scatter_nd_add_cn.rst

@@ -57,4 +57,13 @@ Tensor，数据类型和形状都与 :code:`x` 相同。
 代码示例
 ::::::::::::
 
-COPY-FROM: paddle.scatter_nd_add
+
+                    output = [0, 22, 12, 14, 4, 5]
+
+**示例一图解说明**：
+
+    在这个示例中，通过 Paddle 的 scatter_nd_add 函数对张量 x 进行稀疏加法操作。初始张量 x 为 [0, 1, 2, 3, 4, 5]，通过 index 指定需要更新的索引位置，并使用 updates 中的值进行累加。scatter_nd_add 函数会根据 index 的位置逐步累加 updates 中的对应值，而不是替换原有值，最终得到输出张量为 [0, 22, 12, 14, 4, 5]，实现了对张量部分元素的累加更新而保持其他元素不变。
+    .. figure:: ../../images/api_legend/scatter_nd_add.png
+       :width: 700
+       :alt: 示例一图示
+       :align: center

docs/api/paddle/scatter_nd_add_en.rst

@@ -0,0 +1,69 @@
+.. _en_api_paddle_scatter_nd_add:
+
+scatter_nd_add
+-------------------------------
+
+.. py:function:: paddle.scatter_nd_add(x, index, updates, name=None)
+
+
+
+
+Performs sparse addition on individual values or slices in a Tensor, resulting in an output Tensor.
+
+:code:`x` is a Tensor with a dimension of :code:`R`. :code:`index` is a Tensor with a dimension of :code:`K`, which means that the shape of :code:`index` is :math:`[i_0, i_1, ..., i_{K-2}, Q]`, where :math:`Q \leq R`. :code:`updates` is a Tensor with a dimension of :math:`K - 1 + R - Q` and a shape of :math:`index.shape[:-1] + x.shape[index.shape[-1]:]`.
+
+According to the :math:`[i_0, i_1, ..., i_{K-2}]` of :code:`index`, it selects the corresponding :code:`updates` slice and adds it to the :code:`x` slice obtained by the last dimension of :code:`index`, resulting in the final output Tensor.
+
+Examples:
+
+::
+
+        - Example 1:
+            x = [0, 1, 2, 3, 4, 5]
+            index = [[1], [2], [3], [1]]
+            updates = [9, 10, 11, 12]
+
+          Result:
+
+            output = [0, 22, 12, 14, 4, 5]
+
+        - Example 2:
+            x = [[65, 17], [-14, -25]]
+            index = [[], []]
+            updates = [[[-1, -2], [1, 2]],
+                       [[3, 4], [-3, -4]]]
+            x.shape = (2, 2)
+            index.shape = (2, 0)
+            updates.shape = (2, 2, 2)
+
+          Result:
+
+            output = [[67, 19], [-16, -27]]
+
+
+Parameters
+::::::::::::
+
+    - **x** (Tensor) - The input tensor, data type can be int32, int64, float32, float64.
+    - **index** (Tensor) - The index tensor, data type must be non-negative int32 or non-negative int64. Its dimension :code:`index.ndim` must be greater than 1, and :code:`index.shape[-1] <= x.ndim`
+    - **updates** (Tensor) - The update tensor, which must have the same data type as :code:`x`. Its shape must be :code:`index.shape[:-1] + x.shape[index.shape[-1]:]`.
+    - **name** (str, optional) - For more details, refer to :ref:`api_guide_Name`. Generally, this does not need to be set. Default is None.
+
+Returns
+::::::::::::
+
+A tensor with the same data type and shape as :code:`x`.
+
+Example Code
+::::::::::::
+
+
+                    output = [0, 22, 12, 14, 4, 5]
+
+**Explanation of Example 1**:
+
+In this example, the scatter_nd_add function of Paddle performs sparse addition on the tensor `x`. The initial tensor `x` is `[0, 1, 2, 3, 4, 5]`. The `index` specifies the positions to be updated, and the values in `updates` are used to accumulate them. The scatter_nd_add function will add the corresponding values in `updates` to the specified positions in `x`, rather than replacing the original values. Finally, the output tensor is `[0, 22, 12, 14, 4, 5]`, achieving the cumulative update of specific elements in the tensor while keeping other elements unchanged.
+    .. figure:: ../../images/api_legend/scatter_nd_add.png
+       :width: 700
+       :alt: Example 1 Illustration
+       :align: center