Control inst/doc cleaning of pkgbuild

[gaborcsardi]

From #129

[bbolker]

You said something here that made it sound as though adding Config/build/clean-inst-doc: false to the DESCRIPTION file would disable the annoying (to me, no claims as to whether this is best practice or not!) "Building the package will delete..." behaviour when there is a pre-built vignette in inst/doc. This doesn't seem to do what I want: any chance you could point me to documentation (or an appropriate place in the code) where I can read more/figure out how this works?

[gaborcsardi]

This issue is about implementing that feature.

[bbolker]

Great, thanks! I was confused (i.e., I thought it already existed).