pd-ctl: add scheduler config evict-leader-scheduler (#4371)
pd-ctl: add scheduler config evict-leader-scheduler (#4371)

* Update pd-control.md

* Apply suggestions from code review

* region --> Region

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