Proposal following discussion in #21841
Regarding browser requirements, I went for a minimalistic approach. This is fully open to discussion.
I googled a bit, and it seems that most systems / libraries out there tend to support whatever the "current" version is, as well as "current - 1". That is probably too restrictive for us, but I'm not quite sure what we should recommend as a minimum version.
@syncguru your feedback would be appreciated
@vboctor If there are no objections, I'd suggest to merge this prior to releasing 2.0.0-rc.2
Doc: update system requirements for 2.x
Fixes #21841, #21965
Doc: update client (browser) requirements for 2.x
Doc: set version to 2.0 and reset revision history
README: update requirements for 2.x