minor #15411 [Form] Fix incorrect class name for Twig configurations (ker0x)

This PR was merged into the 5.3 branch.

Discussion
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[Form] Fix incorrect class name for Twig configurations

I made a mistake while writing the Bootstrap 5 configuration documentation.

Commits
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ded36b5 Fix incorrect class name for Twig configurations

Author: javiereguiluz

form/bootstrap5.rst

@@ -61,7 +61,7 @@ configuration:
         // config/packages/twig.php
         use Symfony\Config\TwigConfig;
 
-        return static function(FrameworkConfig $twig) {
+        return static function(TwigConfig $twig) {
             $twig->formThemes(['bootstrap_5_layout.html.twig']);
 
             // ...