Updated instructions for using make_tarball.sh so that the documentation will be installable using the command make www-install.
Updated instructions for using make_tarball.sh so that the documentation will be installable using the command make www-install.

svn path=/trunk/; revision=7798

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot