(Just to clarify my position: I am all for automatizing daunting tasks as much as possible, but this seems to be a little far-fetched.)
I really don't understand the mindset that takes people from "hey look somebody wrote a free piece of software I can use if I want" to "what, now I need to use yet another piece of software for something?"
It's not that I stop people from doing things they want to do. I just wanted to point out that something seemingly simple as writing a README usually does not require yet another tool that has to be learned and – being a dependency – maintained.
There are 11 versions of Sinatra’s README which don’t share any general templates. They should be manually edited after each release. This is kind of thing that needs automatization.
Plus, it is much easier to inject badges by a mixin, not by copypasting and manually changing some elements from your old READMEs.