Windows installation default instructions

Relating to file `install/index.md` and the page https://julialang.org/install/ Based on https://discourse.julialang.org/t/a-graphical-julia-installer-for-windows/128413/47 I think that the default installation option presented to a generic Windows user when clicking Install on [julialang.org](http://julialang.org/) should be the stand-alone graphical installer, that is in fact available from the 'Manual Downloads' page on the site. The reason is that I would bet that the majority/typical user on Windows is not development-oriented (as evidence, see multiple threads on Discourse about the lack of such users) The approach of using a command-line to install juliaup (which I love for development on macOS) is not typical of such users’ way of thinking about installation. I would recommend that the primary and most visible option be that users are directed to the instructions at https://julialang.org/downloads/platform/#windows and most should then download of the `.exe` installer as available from 'Manual Downloads'.