Propagate decision to drop PostScript form of documentation to one
last bit of CMake logic in the build system where I forgot to make the
change, and also for the generated website.
Tested by: Alan W. Irwin <email@example.com> on Linux by
running the scripts/generate_website.sh script described in
README.Release_Manager_Cookbook, and by carefully checking the
local website (especially the html and pdf forms of the docbook
documentation and the html form of the doxygen documentation
that is generated by that script) using the konqueror browser.