Demo installation guide

[Pericles S. Nacionales]

Folks,

The MapServer demo installation guide is now available at
http://mapserver.gis.umn.edu/demo_readme.html.  It is also accessible from
the documentation page of the MapServer web site.  Thanks to all of you who
gave comments and suggestions.  Thanks especially to Matt Wilkie who
provided additional text on error messages and debugging.

-Perry N.