Update re: read-only root filesystem

[Thomas Hood <jdthood@yahoo.co.uk>]

Some progress has been made toward the goal of making
Debian easier to use with a read-only root filesystem.
Action has been taken to remove variable files from /etc/,
or at least to make it possible to do so locally, in the
following packages: cupsys, laptop-net, pppconfig, sysvinit.

Packages that still employ variable files in /etc/ include:
mount, ifupdown, dhcpcd, linuxlogo, ppp, util-linux.
Fortunately, some of the files can be replaced by symlinks.
See my README file at
    http://panopticon.csustan.edu/thood/readonly-root.html
for (incomplete) information.

Many thanks to the maintainers who have been supporting
this effort.
--
Thomas Hood