Update downloads.md

[ChristopherBull]

feat: download link for Windows points to latest

The download link previously pointed to the GitHub repo, which is not a great UX. Added /releases/latest to end of URL to make it easier for people not familiar with GitHub UI.

[calmh]

On the other hand, it currently points to the very extensive installation and usage instructions, which you otherwise wouldn't necessarily be aware or by just following a link to the releases.

[ChristopherBull]

Absolutely fair. It is currently not consistent with the MacOS link (which does go to /releases/latest). If this pull is rejected, I would still recommend consistency between the Mac/Win links (should both go to latest release or the extensive install instructions?), and an easier download UX for on-boarding new users--GitHub is a developer platform, not a good UX for downloading software if you're not familiar with it.

[calmh]

Indeed... lacking a proper website, perhaps the best links for each are https://github.com/Bill-Stewart/SyncthingWindowsSetup/blob/main/README.md resp. https://github.com/syncthing/syncthing-macos/blob/develop/README.md as then you'll come directly to background info, instructions, and the recommended download links fairly high up on each