docs: fix incorrect model validation example (#13470)

Closes #13438

Co-authored-by: AllAwesome497 <47748690+AllAwesome497@users.noreply.github.com>

docs/manual/core-concepts/validations-and-constraints.md

@@ -16,8 +16,10 @@ const User = sequelize.define("user", {
   },
   hashedPassword: {
     type: DataTypes.STRING(64),
+    validate: {
       is: /^[0-9a-f]{64}$/i
     }
+  }
 });
 
 (async () => {