add R-FAQ to htmlxref.cnf

[Sebastian Meyer]

The attached patch adds the R-FAQ 
<https://CRAN.R-project.org/doc/manuals/R-FAQ.html> to the list of R 
manuals (and also switches to the canonical form of the CRAN URL).
This will avoid issues like

    R-intro.texi:216: warning: no htmlxref.cnf entry found for `R-FAQ'

when converting to EPUB, which cannot handle local links to other manuals.

Thanks!

--
Dr. Sebastian Meyer
Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU)
Institute of Medical Informatics, Biometry, and Epidemiology (IMBE)

https://www.imbe.med.fau.de/person/sebastian-meyer/

htmlxref.diff
Description: Text Data