man: fix unused, inaccurate metadata

man: fix unused, inaccurate metadata

Dates aren't shown in the manpages.  So they are not really useful,
and no-one is going to remember to update them.

"<refmiscinfo class="version"></refmiscinfo>" sounds even less useful.

I leave the unused "title" and "productname" tags.  They could
theoretically be useful, and aren't hard to maintain.  We just need to
fix the "title" for udevadm.

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>