[NCL-3186] Add documentation to `close_milestone`
[NCL-3186] Add documentation to `close_milestone`

thauser/pnc-cli,project-ncl/pnc-cli,janinko/pnc-cli,janinko/pnc-cli,thauser/pnc-cli,janinko/pnc-cli,project-ncl/pnc-cli,thauser/pnc-cli,project-ncl/pnc-cli