Yet again Maven has shat upon me from on high by randomly updating a
plugin and changing its behaviour. Previously, if you had a project
configured as a "multiproject" build of modules, the way to include a
link in your parent project's docs to the child documentation was to add
${modules} into the parent's site.xml. No longer! Try this now, and
your mvn will spit out some garbage about your site.xml being malformed
xml, when it plainly isn't. No, now the secret incantation is to put a
menu item in thus: <menu ref="modules"/>. The same goes for ${reports}
and ${parent} presumably. The new syntax is certainly nicer, if you
don't mind the extra wear and tear on your fingers, but I wish they
had just deprecated the old syntax, rather than secretly removing it.
