Improve docs for non-apache webserver configuration

Tillwoofie (http://www.phpbb.com/community/memberlist.php?mode=viewprofile&u=1315072) mentioned lack of security for lighttpd. This is a documentation issue, as we do provide sample config files for lighttpd and nginx in the docs directory.

As per bantu's suggestion, we should extend section 6 (Important (security related) post-Install tasks for all installation methods) of the docs/README.html file.