pd: make some configuration more clear (#4658)
pd: make some configuration more clear (#4658)

* Update pd-configuration-file.md

* Update pd-configuration-file.md

* Apply suggestions from code review

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

* Update pd-configuration-file.md

Co-authored-by: Ryan Leung <98ca95cd24c810cea97a0e53f67d648652b7b2cf@gmail.com>

Co-authored-by: TomShawn <3d0966147538bc5ab020e8dffa2c0b746f9728a6@users.noreply.github.com>
Co-authored-by: Ryan Leung <98ca95cd24c810cea97a0e53f67d648652b7b2cf@gmail.com>
pingcap/docs,pingcap/docs,pingcap/docs