improve scatter_nd doc according to tf version

src/operator/tensor/indexing_op.cc

@@ -573,20 +573,22 @@ Examples::
 .add_argument("indices", "NDArray-or-Symbol", "indices");
 
 NNVM_REGISTER_OP(scatter_nd)
-.describe(R"code(Scatters data into a new tensor according to indices.
+.describe(R"code(Scatters `data` into a new tensor according to `indices`.
 
-Given `data` with shape `(Y_0, ..., Y_{K-1}, X_M, ..., X_{N-1})` and indices with shape
-`(M, Y_0, ..., Y_{K-1})`, the output will have shape `(X_0, X_1, ..., X_{N-1})`,
-where `M <= N`. If `M == N`, data shape should simply be `(Y_0, ..., Y_{K-1})`.
+`indices` is an integer tensor containing indices into a new tensor of shape `shape`.
+The last dimension of `indices` can be at most the rank of `shape`:
 
-The elements in output is defined as follows::
+.. math::
 
-  output[indices[0, y_0, ..., y_{K-1}],
-         ...,
-         indices[M-1, y_0, ..., y_{K-1}],
-         x_M, ..., x_{N-1}] = data[y_0, ..., y_{K-1}, x_M, ..., x_{N-1}]
+indices.shape[-1] <= shape.rank
+
+The last dimension of `indices` corresponds to indices into elements (if `indices.shape[-1] =
+shape.rank`) or slices (if `indices.shape[-1] < shape.rank`) along dimension `indices.shape[-1]`
+of `shape`. `data` is a tensor with shape:
 
-all other entries in output are 0.
+.. math::
+
+indices.shape[-1] + shape[indices.shape[-1]:]
 
 .. warning::
 
@@ -601,6 +603,17 @@ Examples::
   shape = (2, 2)
   scatter_nd(data, indices, shape) = [[0, 0], [2, 3]]
 
+  data = [[[5, 5, 5, 5], [6, 6, 6, 6],
+           [7, 7, 7, 7], [8, 8, 8, 8]],
+          [[5, 5, 5, 5], [6, 6, 6, 6],
+           [7, 7, 7, 7], [8, 8, 8, 8]]]
+  indices = [[0], [2]]
+  shape = (4, 4, 4)
+  scatter_nd(data, indices, shape) = [[[5, 5, 5, 5], [6, 6, 6, 6], [7, 7, 7, 7], [8, 8, 8, 8]],
+                                      [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]],
+                                      [[5, 5, 5, 5], [6, 6, 6, 6], [7, 7, 7, 7], [8, 8, 8, 8]],
+                                      [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]]
+
 )code")
 .set_num_outputs(1)
 .set_num_inputs(2)