On linux, the command to get help in R is simple. Check the option to output to buffer and then enter:

Rscript --slave -e "help(%w, help_type = 'text', try.all.packages = T)"

On windows, it is a bit harder since invoking Rscript will open a console that will exit immediately. The fix is to create a workaround batch file and place it in your search path.

rhelp.bat

@echo off
echo | Rscript --ess -e "help(%1, help_type = 'text', try.all.packages = T)"

Then call that in the Doc command line:

rhelp %w