refine format of dynamic config doc (#2622)
refine format of dynamic config doc (#2622)

* refine format of dynamic config doc

* Update dynamic-config.md

* Update dynamic-config.md

* Update dynamic-config.md

Co-authored-by: Keke Yi <4b13e11d5beb5669a80650bc9e0535372af5b679@users.noreply.github.com>

* Update dynamic-config.md

Co-authored-by: Keke Yi <4b13e11d5beb5669a80650bc9e0535372af5b679@users.noreply.github.com>
pingcap/docs,pingcap/docs,pingcap/docs