feat: validate drupal.docroot

Refs: OD-18

src/ConfigurationData.php

@@ -17,10 +17,15 @@ final class ConfigurationData
             'type' => new Assert\Choice(['mariadb', 'mysql']),
             'version' => new Assert\Type('integer'),
         ],
-        allowExtraFields: false,
     )]
     public array $database;
 
+    #[Assert\Collection(
+        allowExtraFields: false,
+        fields: ['docroot' => new Assert\Choice(['web', 'docroot'])],
+    )]
+    public array $drupal;
+
     #[Assert\Choice(choices: ['node', 'php'])]
     #[Assert\NotBlank]
     public string $language;