Manual pages: order AUTHORS / COPYRIGHT / SEE ALSO / AVAILABILITY consistently

Manual pages: order AUTHORS / COPYRIGHT / SEE ALSO / AVAILABILITY consistently

There is value in ensuring that manual page sections use consistently
named sections, as far as possible, and also that sections have a
consistent order within manual pages. This is one of a series of patches
to place manual page sections in a consistent order.

In this patch, we ensure that the AUTHORS, COPYRIGHT, SEE ALSO, and
AVAILABILITY sections are always placed at the end of the page.

Testing that no gross editing mistake (causing accidental loss or addition
of text) was performed as follows:

    $ cat $(grep '\.SH' -l $(find . -name '*.[1-9]') |sort) | sort > a
    [Apply patch]
    $ cat $(grep '\.SH' -l $(find . -name '*.[1-9]') |sort) | sort > b
    $ diff a b
    $ echo $?
    0

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>