minor #7215 Updated "Authentication System with Guard" Page (powerdan, Daniel Werner)

This PR was merged into the 2.8 branch.

Discussion
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Updated "Authentication System with Guard" Page

Added the (optional) createAuthenticatedToken() Method and dcoumented it.

Also added the braces to the no-argument Method supportsRememberMe.

Also removed the `` Operators in the FAQ section because the bacticks seems not to be resolved in a title on symfony.com

Commits
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d17b180 Accepted Suggestions
cb3abf3 Accepted suggestions in the guard documentation
b2f20f4 Accepted suggestions in the guard documentation
33c0d35 Accepted suggestions in the guard documentation
f8e201f Update guard_authentication.rst

Author: xabbuh

security/guard_authentication.rst

@@ -412,11 +412,18 @@ Each authenticator needs the following methods:
     :class:`Symfony\\Component\\HttpFoundation\\Response` object that helps
     the user authenticate (e.g. a 401 response that says "token is missing!").
 
-**supportsRememberMe**
+**supportsRememberMe()**
     If you want to support "remember me" functionality, return true from this method.
     You will still need to active ``remember_me`` under your firewall for it to work.
     Since this is a stateless API, you do not want to support "remember me"
     functionality in this example.
+    
+**createAuthenticatedToken(UserInterface $user, string $providerKey)**
+    If you are implementing the :class:`Symfony\\Component\\Security\\Guard\\GuardAuthenticatorInterface`
+    instead of extending the :class:`Symfony\\Component\\Security\\Guard\\AbstractGuardAuthenticator`
+    class, you have to implement this method. It will be called
+    after a successful authentication to create and return the token
+    for the user, who was supplied as the first argument.
 
 .. _guard-customize-error:
 
@@ -552,7 +559,7 @@ Frequently Asked Questions
                 ),
             ));
 
-**Can I use this with ``form_login``?**
+**Can I use this with form_login?**
     Yes! ``form_login`` is *one* way to authenticate a user, so you could use
     it *and* then add one or more authenticators. Using a guard authenticator doesn't
     collide with other ways to authenticate.