Include a license file

[cactusdualcore]

I assume contributions are welcome, because this is uploaded to github and available publicly, but as far as I know this falls under rights reserved. I have no background with copyright and only know what I found online, e.g. here.

[cactusdualcore]

This seems to be related to vscode-wgsl, which includes the MIT license, so it really looks like an oversight.

[PolyMeilex]

MIT was defined on crates.io:

cargo-wgsl/Cargo.toml

Line 9 in 955c21b

license = "MIT"

but yeah there should be a full license copy.
Commited here https://github.com/PolyMeilex/cargo-wgsl/blob/master/LICENSE

[cactusdualcore]

Thanks a lot