doc: clarify that "cert" and "key" are not paths
doc: clarify that "cert" and "key" are not paths

Credit: da39a3ee5e6b4b0d3255bfef95601890afd80709@rvedotrc
PR-URL: https://github.com/npm/npm/pull/12415

Volune/npm,evocateur/npm,DaveEmmerson/npm,lxe/npm,misterbyrne/npm,misterbyrne/npm,TimeToogo/npm,midniteio/npm,Volune/npm,evocateur/npm,DaveEmmerson/npm,chadnickbok/npm,chadnickbok/npm,midniteio/npm,evocateur/npm,DaveEmmerson/npm,lxe/npm,chadnickbok/npm,midniteio/npm,Volune/npm,misterbyrne/npm,lxe/npm,TimeToogo/npm,TimeToogo/npm