It tells me that is has something to do with login, "without state" (whatever this means in this context) and that it is somehow not a "big service" but very "micro", so probably independent. Stateless and microservice can mean so many things.
A microservice is a service that does only one thing, and does it simply.
Something stateless doesn't keep state - after an interaction with a client, nothing has changed in the service itself.
A stateless authentication microservice is something I would expect to run, listen on a port for some sort of authentication credentials, and return either some sort of authorizarion token or an authentication error.
I don't see where the confusion comes from.
Asking to do a pull request or create an issue is just a polite way of saying fuck off.
Perhaps you could describe what details you would like to see in the issue? :)
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In seriousness, noobish me would like to understand more what this is and when I should use it.
There you go: https://github.com/lipp/login-with/issues/25
Also maybe a sentence why this is neat and should be used...