add new chapter "R project websites"

[SaranjeetKaur]

I think we might want to move this to a new chapter. There are various websites that the R Core team maintain, each with their own way to report issues (R FAQ, Windows FAQ, Mac FAQ, R project web-site, CRAN website). These are all outside the scope of Bugzilla. This might be a new section in the Bug reporting chapter (since we also document there how to report bugs in non-R-Core maintained packages), or a small chapter on "R project websites". Perhaps the latter is useful as there are also other sites on the r-project domain, like translation.r-project,org and contributor.r-project.org that could be good to document briefly somewhere.

Originally posted by @hturner in https://github.com/r-devel/rdevguide/pull/66#discussion_r982075017