Update docs to reflect the status of .NET Standard in 2020 about standard HOT 2 CLOSED

This repo is indeed frozen in time - a time before Microsoft decided that supporting Framework forever wasn't worth the pain, and hence that Standard was no longer necessary.

Microsoft being Microsoft, though, you're not going to be able to get an admission that they've killed off a certain product/technology, so this repo will likely remain both untouched, and quietly ignored, by them for the rest of eternity. It's like a monument to the potential for a horrifying alternate reality; a world where Framework was allowed to remain a shambling undead horror to forever haunt devs with nightmares of backwards compatibility.

They should update the docs as you've mentioned, then archive this repo.

from standard.

The README in the default branch is reflecting this reality now.

from standard.