suggestion: have `deno coverage --html` generate coverage badge

[iuioiua]

Like how code coverage services do. You can put the badge in the README of your package and have it link to the output generated from deno coverage --html in /coverage/html/index.html. This would remove the need for developers to sign up for 3rd party coverage services.

It'd be cool if the badge's background corresponded with the amount of coverage, too. For example, red would indicate 0% coverage, and green would indicate 100% coverage.

From the Standard Library:

[iuioiua]

Maybe we should use the shields crate. WDYT, @kt3k?

[kt3k]

I think this can be done with simple string operations. shields crate seems overkill for us which tries to solve more general problem