Cairo is not supported

[seanpm2001]

Cairo appears to be missing from the list. Here is how a Hello World program is written:

use debug::PrintTrait;
fn main() {
    'Hello, World'.print();
}

According to :octocat: Cairo-book/Cairo-book.github.io

The extension is .cairo so the file should be placed at ///C/Cairo.cairo

This language should definitely be included, as it is notable enough to be listed in the GitHub Linguist, meaning it has a notable amount of usage by more than a handful of people.