Remove documentation on half-baked support for multi-factor auth

README.md

@@ -81,7 +81,6 @@ Migrating from an earlier version of this project? See our [upgrade guide](Migra
    * [Creating a random string](#creating-a-random-string)
    * [Creating a UUID v4 as per RFC 4122](#creating-a-uuid-v4-as-per-rfc-4122)
  * [Reading and writing session data](#reading-and-writing-session-data)
- * [Implementing multi-factor authentication](#implementing-multi-factor-authentication)
 
 ### Creating a new instance
 
@@ -805,24 +804,6 @@ $uuid = \Delight\Auth\Auth::createUuid();
 
 For detailed information on how to read and write session data conveniently, please refer to [the documentation of the session library](https://github.com/delight-im/PHP-Cookie#reading-and-writing-session-data), which is included by default.
 
-### Implementing multi-factor authentication
-
-You can pass a callback, e.g. an anonymous function, to the two methods `login` or `loginWithUsername` as their fourth parameter. Such a callback could look like this:
-
-```php
-function ($userId) {
-    // ...
-
-    return false;
-    // or
-    // return true;
-}
-```
-
-The callback will be executed if (and only if) authentication is successful, but it will run *right before* completing authentication. This lets you hook into the login flow.
-
-In that callback, you receive the authenticating user's ID as the only parameter. Return `true` from the callback to let authentication proceed, or return `false` to cancel the attempt. Be ready to catch the `AttemptCancelledException` in the latter case.
-
 ## Frequently asked questions
 
 ### What about password hashing?