The description of the password hashers in the reference isn't up to date for Symfony 5.3.

"Auto" now always uses bcrypt (see#14980 and#14992), but it wasn't reflected here. I initially thought this was a bug in the password hasher component itself and created asymfony/symfony#41646, but I've since learned that the switch to bcrypt was intentional :-)

I updated all the hasher descriptions a bit and removed the part about sodium before PHP 7.2 because Symfony 5.3 requires PHP >= 7.2. I also added an extra paragraph for the bcrypt hasher because it was a bit mixed into the description of the "auto" hasher.