Provide both html and pdf vignettes?

[florianhartig]

Request via email for a pdf version of the vignette.

Theoretically, it should be possible to do this automatically, see

• https://stackoverflow.com/questions/31214524/how-do-i-produce-r-package-vignettes-in-multiple-formats
• https://community.rstudio.com/t/html-and-pdf-vignette-reasonable/132749

But I'm not sure if it's worth the overhead. Possibly keep a vignette on the DHARMa website?