Adapt to changed RHOME in runner for pkgup GHA job (#6727)

* Print debugging of pkgup GHA

* more comments to enable running on branch for the moment

* Try next step

* RTFM to avoid starting an R session

* missing components

* OK looks right now

* whitespace

Author: MichaelChirico

.github/workflows/pkgup.yaml

@@ -50,7 +50,7 @@ jobs:
           cp -R ${{ env.R_LIBS_USER }} library
           R CMD INSTALL --library="library" $(ls -1t data.table_*.tar.gz | head -n 1) --html
           mkdir -p doc/html
-          cp /usr/share/R/doc/html/{left.jpg,up.jpg,Rlogo.svg,R.css,index.html} doc/html
+          cp $(R RHOME)/doc/html/{left.jpg,up.jpg,Rlogo.svg,R.css,index.html} doc/html
           Rscript -e 'utils::make.packages.html("library", docdir="doc")'
           sed -i "s|file://|../..|g" doc/html/packages.html
           mkdir -p public