message: Fix link to readme.pdf
diff: @@ -240,9 +240,9 @@ Documentation
  =============
  The following [API
  -documentation](http://www.sdvis.org/ospray/download/OSPRay_readme_devel.pdf "OSPRay Documentation")
  +documentation](http://www.sdvis.org/ospray/download/OSPRay_readme.pdf "OSPRay Documentation")
  of OSPRay can also be found as a [pdf
  -document](http://www.sdvis.org/ospray/download/OSPRay_readme_devel.pdf "OSPRay Documentation").
  +document](http://www.sdvis.org/ospray/download/OSPRay_readme.pdf "OSPRay Documentation").
  For a deeper explanation of the concepts, design, features and
  performance of OSPRay also have a look at the IEEE Vis 2016 paper
  