backport some tweaks from 5.0 docs

Author: xabbuh

security/guard_authentication.rst

@@ -333,7 +333,7 @@ Finally, configure your ``firewalls`` key in ``security.yml`` to use this authen
                     'logout'         => true,
                     'guard'          => [
                         'authenticators'  => [
-                            TokenAuthenticator::class
+                            TokenAuthenticator::class,
                         ],
                     ],
                     // ...
@@ -419,7 +419,7 @@ Each authenticator needs the following methods:
     the user authenticate (e.g. a 401 response that says "token is missing!").
 
 **supportsRememberMe()**
-    If you want to support "remember me" functionality, return true from this method.
+    If you want to support "remember me" functionality, return ``true`` from this method.
     You will still need to activate ``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.
@@ -428,7 +428,8 @@ Each authenticator needs the following methods:
     If you are implementing the :class:`Symfony\\Component\\Security\\Guard\\AuthenticatorInterface`
     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
+    after a successful authentication to create and return the token (a
+    class implementing :class:`Symfony\\Component\\Security\\Guard\\Token\\GuardTokenInterface`)
     for the user, who was supplied as the first argument.
 
 The picture below shows how Symfony calls Guard Authenticator methods: