[docs] fix broken MS MPI link in Installation Guide

[jameslamb]

The "Link Checks" job is currently failing with the following error.

URL        `https://www.microsoft.com/en-us/download/details.aspx?id=100593'
Name       `MS MPI'
Parent URL file:///home/runner/work/LightGBM/LightGBM/docs/_build/html/Installation-Guide.html, line 596, col 28
Real URL   https://www.microsoft.com/en-us/download/404Error.aspx
Check time 1.069 seconds
Size       92.45KB
Info       Redirected to
           `https://www.microsoft.com/en-us/download/404Error.aspx'.
Result     Error: 404 Not Found

Most recent build was 10 hours ago: https://github.com/microsoft/LightGBM/actions/runs/782291613

I see that broken download links have also been reported in the MS MPI repo: microsoft/Microsoft-MPI#54

This PR proposes linking to the official release notes for MS MPI instead of to aa specific download in the Microsoft Download center. That should fix the failing build and I think it's a better link anyway because users can read release notes AND get downloads there.

[jameslamb]

ugh sorry, I don't understand how these extra commits made it onto this branch.

Will fix it. fixed

[StrikerRUS]

Thanks!

[github-actions]

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