This alias is to make autocomplete faster via xfun::install_github, because
most remotes::install_* functions are never what I want. I only use
install_github and it is inconvenient to autocomplete it, e.g.
install_git always comes before install_github, but I never use it. In
RStudio, I only need to type xfun::ig to get xfun::install_github.
install_github(...)Arguments to be passed to remotes::install_github().