Add todo item for an httpauth example.

[ikiwiki] / doc / todo / httpauth_example.mdwn

ikiwiki should supply an example .htaccess file for use with HTTP
authentication (perhaps as a [[tip|tips]]), showing how to authenticate the
user for edits without requiring authentication for the entire wiki. (Ideally,
recentchanges should work without authentication as well, even though it goes
through the CGI.) --[[JoshTriplett]]