Typelevel shields

[rossabaker]

@j-mie6 is asking on #70 about adding a badge. It's not a requirement, but I think they're nice branding for us and a point of pride for projects. Let's standardize.

Proposal

These use the colors from the Typelevel logo:

Organization projects

![Typelevel Organization Project](https://img.shields.io/badge/typelevel-organization%20project-FF6169.svg)

Affiliate projects

![Typelevel Affiliate Project](https://img.shields.io/badge/typelevel-affiliate%20project-FFB4B5.svg)

Prior art

Two attempts that predate the Organization / Affiliate categorization:

• From Gitter, and
• From http4s,

[jducoeur]

I like it!

[zmccoy]

That looks great to me.

[rossabaker]

Edit: fixed the alt text on the affiliate badges.

I don't think we need a formal vote. We could turn this into a Good First Issue on various projects for new people who want to get their feet wet with the PR flow.