fix arange api in ndarray.md (#789)
fix arange api in ndarray.md (#789)

* fix arange api in ndarray.md

* fix arange api in ndarray.md

Co-authored-by: Riddler <40611f021056d0dbb6315895ef470af86cd7d359@qq.com>
Co-authored-by: Aston Zhang <8c8ad147955c78e3333e2e548e1071c85a8292c7@users.noreply.github.com>
mli/gluon-tutorials-zh,mli/gluon-tutorials-zh,d2l-ai/d2l-zh,d2l-ai/d2l-zh,mli/gluon-tutorials-zh,mli/gluon-tutorials-zh,d2l-ai/d2l-zh