There is a missing link on this page: http://meta.stackoverflow.com/privileges/vote-down
It also seems broken on SO. Could someone take a look?
Looks like someone simply forgot to add that link.
It's pretty obvious what that was meant to link to, so I fixed it here; all privilege pages are wikis on MSO. The change will propagate to all other Stack Exchange sites in… actually I don't know, this is done manually.