br: update adaptive GC description (#4885)
br: update adaptive GC description (#4885)

* Br adaptive GC description

Br adaptive GC description
https://github.com/pingcap/br/pull/257

* Update backup-and-restore-use-cases.md

增加了修复版本链接, 请帮忙检查

* update

增加了修复版本链接, 请帮忙检查

* refine language

* Update br/backup-and-restore-use-cases.md

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