[Rd] URL for a vignette on CRAN?

[Spencer Graves]

       How can I get a full URL for anything on CRAN?


       Using Safari, Google Chrome, and Firefox under OS X 10.11.2, I 
select a CRAN mirror from "www.r-project.org" and get a URL like 
"https://cran.rstudio.com/".  Then I select "packages" and get a 
different web page, but the URL displayed doesn't change.  I'd like to 
access the full URL of a vignette in a package, but modern web browsers 
hide that detail.


       Thanks,
       Spencer Graves