Fix namespace/filepath mismatches found by DOCtor-RST

- Fix Author filepath from src/EntityAuthor.php to src/Entity/Author.php
- Fix User namespace from App\Entity\User to App\Entity

Author: OskarStark

reference/constraints/Choice.rst

@@ -83,7 +83,7 @@ If your valid choice list is simple, you can pass them in directly via the
 
     .. code-block:: php
 
-        // src/EntityAuthor.php
+        // src/Entity/Author.php
         namespace App\Entity;
 
         use Symfony\Component\Validator\Constraints as Assert;
@@ -170,7 +170,7 @@ constraint.
 
     .. code-block:: php
 
-        // src/EntityAuthor.php
+        // src/Entity/Author.php
         namespace App\Entity;
 
         use Symfony\Component\Validator\Constraints as Assert;

reference/constraints/Compound.rst

@@ -53,7 +53,7 @@ You can now use it anywhere you need it:
     .. code-block:: php-attributes
 
         // src/Entity/User.php
-        namespace App\Entity\User;
+        namespace App\Entity;
 
         use App\Validator\Constraints as Assert;
 
@@ -89,7 +89,7 @@ You can now use it anywhere you need it:
     .. code-block:: php
 
         // src/Entity/User.php
-        namespace App\Entity\User;
+        namespace App\Entity;
 
         use App\Validator\Constraints as Assert;
         use Symfony\Component\Validator\Mapping\ClassMetadata;