How to contribute to this document?

I have removed the InterFAQ from this answer, as it has become
clear that people prefer the familiar approach of emailing me
to that of contributing via the web, and (in turn) the InterFAQ
contents has not been maintained for some time.  Thomas Boutell
has since introduced a somewhat similar project, the OpenFAQ.
Just mail me.  ( mailto:help@pvdlab.net )