fix download broken links + update download links to v2.1.0

[ramigs]

fixing broken download links for Mac and Windows.

also noticed that a new version was released yesterday, so updated the links to point to v2.1.0.
pls let me know if keeping v2.0.0 is intended and I'll update the PR.

[jamaljsr]

Thanks so much for catching this. I did forget to update the README with the latest release.

[ramigs]

btw, to avoid having to manually update at each release, has it been considered linking to the latest release? https://docs.github.com/en/repositories/releasing-projects-on-github/linking-to-releases

or is it unsuitable because some releases are rc and therefore not to be linked?
if so, maybe could be considered introducing tag stable and linking to it.

however, this change would require file names to not have the version anymore (not sure if it's a hard requirement)

[jamaljsr]

Thanks for the suggestion. I would prefer to keep the version in the file names. This hasn't been an issue with past releases. I was just rushing this time and did the release without referring to the documented release process, which was a mistake.