How do you store refresh tokens?

[cottton]

I suggest to NOT post how you store your tokens. Dont give hints out in the public.
This post here is more to bring attention to this topic, so ppl do not store refresh tokens as plain text in the db.

Background: #119 (comment)

TL;DR: plain text refresh token in db means if there is a db leak, then the attacker can login with the token.
Means: the refresh token should be handled like a clear text password.

I really would like to see a pretty short but clear description in the readme
that makes clear: the refresh token should be handled like a clear text pw. It must stored hashed in the db.

And since this is PHP-jwt i suggest an example with PHP password_hash() | password_verify().

Thank you.