Of the 55 questions currently tagged helpfile, 13 of them are somewhat related to documentation.
The remainder are questions about all kinds of things, for example:
I can't open nautilus after executing rm -rf ~/.ddd/
Can I sell a modified version of Ubuntu?
Ubuntu 16.04 not detecting HDMI
I think that people are using this tag when they want help ...
No. Not unless version 2 is somehow completely different and someone can be an expert in WSL2 and not in WSL. The version can be mentioned in the body, that is helpful, but having a different tag for every version of a tool that comes out will just complicate things.
So I'd say we really don't need separate tags for separate versions of WSL.