[Security] [Login Link] Give some security-related infos: link length, used algorithm, etc.

[ThomasLandauer]

Some questions which I think should be answered on https://symfony.com/doc/current/security/login_link.html#invalidate-login-links

1. What is the length of the generated link ("signed URL")? Is this configurable?
2. Which signing algorithm is used? Is this configurable? Does it use some salt?
3. Show an example of such a URL