The files http://previsat.sourceforge.net/fichiers/PreviSat_fr.pdf and
http://previsat.sourceforge.net/fichiers/PreviSat_en.pdf should be
downloaded into this directory at post-installation time. If this did
not occur, you can try to get them manually.

Also, if a new version of PreviSat is released, unless you purge the
old PDF files, new files will not be downloaded automatically.
