Typos in docs

Somehow, these have gone unnoticed for quite some time.
Escape hatch for the restrictive umask

Some things should not be run with the restrictive umask.
This provides a means to do so: do_readable.
Remove superfluous debugging
Add support for IPv6 with dhcpcd (FS#39531)

This requires dhcpcd 6.4.0 or newer.
1.8 release updates