update roi doc in roi_pool and roi_align (#19036)

* update roi doc in roi_pool and roi_align, test=develop

paddle/fluid/API.spec

@@ -170,8 +170,8 @@ paddle.fluid.layers.lrn (ArgSpec(args=['input', 'n', 'k', 'alpha', 'beta', 'name
 paddle.fluid.layers.pad (ArgSpec(args=['x', 'paddings', 'pad_value', 'name'], varargs=None, keywords=None, defaults=(0.0, None)), ('document', '36b6e58678956585e5b30aa3de123a60'))
 paddle.fluid.layers.pad_constant_like (ArgSpec(args=['x', 'y', 'pad_value', 'name'], varargs=None, keywords=None, defaults=(0.0, None)), ('document', '95aa1972983f30fe9b5a3713e523e20f'))
 paddle.fluid.layers.label_smooth (ArgSpec(args=['label', 'prior_dist', 'epsilon', 'dtype', 'name'], varargs=None, keywords=None, defaults=(None, 0.1, 'float32', None)), ('document', '214f1dfbe95a628600bbe99e836319cf'))
-paddle.fluid.layers.roi_pool (ArgSpec(args=['input', 'rois', 'pooled_height', 'pooled_width', 'spatial_scale'], varargs=None, keywords=None, defaults=(1, 1, 1.0)), ('document', 'ceedc8c22752c623d6e1ea2e8df0f43f'))
-paddle.fluid.layers.roi_align (ArgSpec(args=['input', 'rois', 'pooled_height', 'pooled_width', 'spatial_scale', 'sampling_ratio', 'name'], varargs=None, keywords=None, defaults=(1, 1, 1.0, -1, None)), ('document', '6f65342f646ef04ae705080a7dfee63f'))
+paddle.fluid.layers.roi_pool (ArgSpec(args=['input', 'rois', 'pooled_height', 'pooled_width', 'spatial_scale'], varargs=None, keywords=None, defaults=(1, 1, 1.0)), ('document', '49368d724023a66b41b0071be41c0ba5'))
+paddle.fluid.layers.roi_align (ArgSpec(args=['input', 'rois', 'pooled_height', 'pooled_width', 'spatial_scale', 'sampling_ratio', 'name'], varargs=None, keywords=None, defaults=(1, 1, 1.0, -1, None)), ('document', '9a7a3b88a4fae41d58d3ca9b10ba0591'))
 paddle.fluid.layers.dice_loss (ArgSpec(args=['input', 'label', 'epsilon'], varargs=None, keywords=None, defaults=(1e-05,)), ('document', '7e8e4bf1f0f8612961ed113e8af8f0c5'))
 paddle.fluid.layers.image_resize (ArgSpec(args=['input', 'out_shape', 'scale', 'name', 'resample', 'actual_shape', 'align_corners', 'align_mode'], varargs=None, keywords=None, defaults=(None, None, None, 'BILINEAR', None, True, 1)), ('document', 'a29488d94d9a4bc4434d8a3529b4c6fe'))
 paddle.fluid.layers.image_resize_short (ArgSpec(args=['input', 'out_short_len', 'resample'], varargs=None, keywords=None, defaults=('BILINEAR',)), ('document', 'bd97ebfe4bdf5110a5fcb8ecb626a447'))

python/paddle/fluid/layers/nn.py

@@ -7513,7 +7513,11 @@ def roi_pool(input, rois, pooled_height=1, pooled_width=1, spatial_scale=1.0):
 
     Args:
         input (Variable): ${x_comment}
-        rois (Variable): ROIs (Regions of Interest) to pool over.
+        rois (Variable): ROIs (Regions of Interest) to pool over.It should be
+                         a 2-D LoDTensor of shape (num_rois, 4), the lod level
+                         is 1. Given as [[x1, y1, x2, y2], ...], (x1, y1) is
+                         the top left coordinates, and (x2, y2) is the bottom
+                         right coordinates.
         pooled_height (integer): ${pooled_height_comment} Default: 1
         pooled_width (integer): ${pooled_width_comment} Default: 1
         spatial_scale (float): ${spatial_scale_comment} Default: 1.0
@@ -7569,7 +7573,11 @@ def roi_align(input,
 
     Args:
         input (Variable): ${x_comment}
-        rois (Variable): ROIs (Regions of Interest) to pool over.
+        rois (Variable): ROIs (Regions of Interest) to pool over.It should be
+                         a 2-D LoDTensor of shape (num_rois, 4), the lod level
+                         is 1. Given as [[x1, y1, x2, y2], ...], (x1, y1) is
+                         the top left coordinates, and (x2, y2) is the bottom
+                         right coordinates. 
         pooled_height (integer): ${pooled_height_comment} Default: 1
         pooled_width (integer): ${pooled_width_comment} Default: 1
         spatial_scale (float): ${spatial_scale_comment} Default: 1.0