Fix alignment documentation:
- while it renders fine on the web, it's stripped from man pages.
Inline HTML renders fine in some cases, but tables don't.
There's no unified (remark) plugin that works well with headless
tables pandoc supports as well, so the only way to achieve a similar
effect is to leave header cells empty.
Signed-off-by: Tin Švagelj <tin.svagelj@live.com>