[Windows] rustup-init.exe's on-screen instructions could be better

[jnachtigall]

I wanted to install rust in order to do cargo install <various-tools>. I see few issues here when gettings started:

1. The on-screen instructions talk about version 2015 but the site where one should download says 2017. This confused me while searching for the right version:
   

2. The site where one downloads is full of text and clutter and various download options. Took me a few moments to read the page and find the right software to download and install.

3. Then I tried ruseup-init.exe again, but it still complained about about missing C++ build tools. Turns out that the software bundle installed in step 2 does not by default install the C++ build tools. So back to the Build Tools for Visual Studio 2017 and checking the right extra checkbox and reinstall.

Step 2 and 3 take about 2-3 hours and lots of disk space.

Actionable things that could be better here to improve Onboarding:

1. Chance on-screen instructions to refer to 2017 and not the 2015 version.
2. Maybe add a html guide with screenshots showing which software to download and which checkboxes to hit while installing. Or even better a GUI installer with screenshots.
3. Also tell the user in the guide that it might take some time and also how much space it will take up on the hard drive.

Related to #1122.

PS As a side note I already tried to install some weeks ago and stopped at step 2 then noticing that I had not enought disk space.

[shepmaster]

For what it's worth, this is a recent change on Microsoft's side. I followed the rustup instructions about 2 weeks ago and I installed the 2015 build tools. The change to 2017 by default presumably happened in that time frame.

In fact, they haven't even fully updated their HTML:

[shepmaster]

An illustrated guide (2018-03-02)

1. Navigate to the link provided by rustup and click the friendly purple button:

2. Filter the download list to find the "Build Tools for Visual Studio 2017" and download the installer:

3. Open the installer and click continue:

4. This takes a minute or two to download the rest of the installer files:

5. Select the build tools. It shows you how much disk space will be used (about 5 GB for the build tools in my case). Click install:

6. Wait. This took about 30 minutes in a 64-bit Windows 10 VM on a 2012 Macbook Pro.

7. Installed

8. Resume the Rust installer

9. Installed!

10. Make your hello world

[jnachtigall]

@shepmaster Awesome guide.

But these steps also show how much fraction there is during the installation. If you compare to ecommerce checkout (make it as simple as possible) and would compare the actual people who want to install rust on Windows and the actual people who finish this step, then this "conversion rate" could probably be much higher if the VS C++ build where automatically part of the rust installation.

FWIW, I also think this change from 2015 to 2017 did not change in the last weeks because I already tried the same step 2, 3 montns ago and then I already had this "which version is right?" confusion and cancelled the whole thing.

I think this is something the rust team might want to fix before the big Rust 2018 release.

[g2p]

A caveat to these instructions:
I also needed to install vswhere to be able to use the visual studio build tools (might be a 2019 change).
scoop install vswhere was the most convenient way for me to get it, YMMV.