Fix dead link for Syntax.md (#3605)
Fix dead link for Syntax.md (#3605)

Fix dead link for Syntax.md

Signed-off-by: Yongxin Wang <2e5ef127fa0f4f81b8a9306e97fa79837f394132@sogou-inc.com>
onnx/onnx,onnx/onnx,onnx/onnx,onnx/onnx