Main page download link improvements

Hi,

Currently (and for as long as I can remember, at least 15? years) the shiny
"Download" button on the www.debian.org main page has linked directly to
the current amd64 netinst iso image, [1] at the time of writing.

The button is technically accurate - clicking it does initiate a download -
but in my opinion it is the bare minimum and debian should have higher
standards.

Instead, that shiny "Download" button should go to a landing page with the
following:

- an (optionally automatic) direct download link to the amd64 netinst iso,
as in [1]
- instructions for verifying the iso, an important step, or a link to said
instructions
- a link to the debian Install Guide
- links for alternate download servers, in case of users who can't reach
cdimage.debian.org
- and finally, a link to the classic distrib page, [2].

This proposal is not dissimilar to our cousin Ubuntu's download interface,
[3]. Fedora and Arch also employ landing pages in between the "Download"
button and the actual installer image.

I have a lot of free time at present and have done web hacking before, so
I'd be happy to do some or all of the legwork on this, if you point me to
the current templates, style guide, or what have you.

I hope this helps to improve debian.org for all of us!

Jesse (sney)


[1]
https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-10.9.0-amd64-netinst.iso
[2] https://www.debian.org/distrib/index.en.html
[3]
https://ubuntu.com/download/desktop/thank-you?version=20.04.2.0&architecture=amd64