minor #5685 Fix indentation in some annotations (iamdto)

This PR was merged into the 2.3 branch.

Discussion
----------

Fix indentation in some annotations

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets | -

Commits
-------

ca494e4 Fix indentation in some annotations

Author: xabbuh

book/validation.rst

@@ -729,19 +729,19 @@ user registers and when a user updates their contact information later:
         class User implements UserInterface
         {
             /**
-            * @Assert\Email(groups={"registration"})
-            */
+             * @Assert\Email(groups={"registration"})
+             */
             private $email;
 
             /**
-            * @Assert\NotBlank(groups={"registration"})
-            * @Assert\Length(min=7, groups={"registration"})
-            */
+             * @Assert\NotBlank(groups={"registration"})
+             * @Assert\Length(min=7, groups={"registration"})
+             */
             private $password;
 
             /**
-            * @Assert\Length(min=2)
-            */
+             * @Assert\Length(min=2)
+             */
             private $city;
         }
 
@@ -918,13 +918,13 @@ username and the password are different only if all other validation passes
         class User implements UserInterface
         {
             /**
-            * @Assert\NotBlank
-            */
+             * @Assert\NotBlank
+             */
             private $username;
 
             /**
-            * @Assert\NotBlank
-            */
+             * @Assert\NotBlank
+             */
             private $password;
 
             /**