Update deploy-tidb-lightning.md (#3963)
Update deploy-tidb-lightning.md (#3963)

* Update deploy-tidb-lightning.md

* Apply suggestions from code review

Co-authored-by: TomShawn <3d0966147538bc5ab020e8dffa2c0b746f9728a6@users.noreply.github.com>
pingcap/docs,pingcap/docs,pingcap/docs