Review Shields descriptions

We describe Shields in different ways in different places:
* on GitHub:
> Concise, consistent, and legible badges in SVG and raster format
* on Twitter:
> Quality metadata badges for open source projects.
* on OpenCollective:
> Concise, consistent, and legible badges… in a readme near you
* ...

Is there room for improvement or making things more consistent? Or are we happy with the current state of these headlines? Either way, I think there's value in having an informal discussion about how we communicate about what Shields is.

Compare the descriptions quoted for GitHub, Twitter, and OpenCollective, then review the other places where Shields is described. The issue does not name files or a specific wording change; it is complete only when the project agrees on whether the headlines need improvement and what consistent description to use.

Written by the indexing model from the issue text.