net-firewall/nftables: Move skel files

net-firewall/nftables: Move skel files

Currently the ebuild installs the skeleton files directly
into the ebuild's doc directory. In 0.9.0-r5 the intention
was installing them into a skels folder (although this was not
done correctly).

Replace the sed rules so that the skeleton files are installed
into the skel folder. This will be cleaner if for some reason
nftables adds further documentation on the future. It is also
easier to perform this change now than once we stabilize.

Bug: https://bugs.gentoo.org/671254
Signed-off-by: Francisco Blas Izquierdo Riera (klondike) <klondike@gentoo.org>
Package-Manager: Portage-2.3.76, Repoman-2.3.11
Signed-off-by: Matthew Thode <prometheanfire@gentoo.org>