(chore:) Update wiki pages once v3.0.0 is released

[grantmcdermott]

There's going to be a lot of outdated information...

[eitsupi]

Doing it manually is far too tedious, so I think the most efficient way is for someone with push privileges to load the vscode-R source code into LLM and update it.
If no one else does it, I'll do it (though I can't guarantee the timing).

[eitsupi]

(This needs to be done after the 3.0.0 release, so I've moved the milestone.)