Move the directive documentation into its own underlay, separate from basewiki,...
[ikiwiki] / underlays / smiley /
drwxr-xr-x   ..
lrwxrwxrwx 17 smileys -> ../../doc/smileys
lrwxrwxrwx 22 smileys.mdwn -> ../../doc/smileys.mdwn