Make doc/votl_readme.txt distro-friendly.

Another Fedora-originated patch.

The mention of problems with Debian's syntax on is not true for at least
two stable releases of Debian, so I think we could let it go. Also, it
is IMHO The Right Thing™ to push users towards packaged plugins.
Merge pull request #34 from mcepl/make_README_more_distribution_friendly

Make readme more distribution friendly