Add docs on validation constraints

Author: scheb

doc/providers/google.rst

@@ -232,3 +232,8 @@ Events
 ------
 
 See :doc:`Events </events>`
+
+Validating Google Authenticator Codes in Forms
+----------------------------------------------
+
+See :doc:`Validating Two-Factor Codes in Forms </validator_constraints>`

doc/providers/totp.rst

@@ -251,3 +251,8 @@ Events
 ------
 
 See :doc:`Events </events>`
+
+Validating TOTP Codes in Forms
+------------------------------
+
+See :doc:`Validating Two-Factor Codes in Forms </validator_constraints>`

doc/validator_constraints.rst

@@ -0,0 +1,39 @@
+Validating Two-Factor Codes in Forms
+=====================================
+
+When building forms that require users to enter a two-factor authentication code, you can use the built-in validation
+constraints provided by the bundle to automatically verify the code against the authenticator provider.
+
+TOTP Code Validation
+--------------------
+
+Use the ``UserTotpCode`` constraint when you want to validate codes from the **TOTP** authentication provider.
+
+.. code-block:: php
+
+    use Scheb\TwoFactorBundle\Security\TwoFactor\Validator\Constraints\UserTotpCode;
+    use Symfony\Component\Validator\Constraints as Assert;
+
+    class SecuritySettingsForm
+    {
+        #[Assert\NotBlank(message: 'Please enter your authentication code')]
+        #[UserTotpCode(message: 'The authentication code is invalid')]
+        public string $totpCode;
+    }
+
+Google Authenticator Code Validation
+------------------------------------
+
+Use the ``UserGoogleTotpCode`` constraint when you want to validate codes from the **Google Authenticator** provider.
+
+.. code-block:: php
+
+    use Scheb\TwoFactorBundle\Security\TwoFactor\Validator\Constraints\UserGoogleTotpCode;
+    use Symfony\Component\Validator\Constraints as Assert;
+
+    class LoginForm
+    {
+        #[Assert\NotBlank(message: 'Please enter your authentication code')]
+        #[UserTotpCode(message: 'The authentication code is invalid')]
+        public string $authCode;
+    }