docs(mge): warp_perspective, gather & scatter

GitOrigin-RevId: f2436e850177b061c6bf7376d3f5b786baa6143c

imperative/python/megengine/functional/nn.py

@@ -884,6 +884,10 @@ def warp_perspective(
     :param interp_mode: interpolation methods. Default: "LINEAR"
     :return: output tensor.
 
+    Note:
+
+    The transformation matrix is the inverse of that used by `cv2.warpPerspective`.
+
     Examples:
 
     .. testcode::

imperative/python/megengine/functional/tensor.py

@@ -391,6 +391,7 @@ def _get_idx(index, axis):
 
 
 def gather(inp: Tensor, axis: int, index: Tensor) -> Tensor:
+    # TODO: rewrite doc
     r"""Gathers data from input tensor on axis using index.
 
     For a 3-D tensor, the output is specified by::
@@ -462,6 +463,7 @@ def gather(inp: Tensor, axis: int, index: Tensor) -> Tensor:
 
 
 def scatter(inp: Tensor, axis: int, index: Tensor, source: Tensor) -> Tensor:
+    # TODO: rewrite doc
     r"""Writes all values from the tensor source into input tensor
     at the indices specified in the index tensor.