minor #9386 Typo fix (scrummerlp)

This PR was submitted for the master branch but it was merged into the 3.4 branch instead (closes #9386).

Discussion
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Typo fix

`Symfony\Component\OptionsResolver\OptionsResolver::setAllowedtypes` method doesn't exist
it's `setAllowedTypes`.

Commits
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a04d8e0 Fixed small typo mistake

Author: javiereguiluz

components/options_resolver.rst

@@ -326,7 +326,7 @@ correctly. To validate the types of the options, call
 
             // check all items in an array recursively for a type
             $resolver->setAllowedTypes('dates', 'DateTime[]');
-            $resolver->setAllowedtypes('ports', 'int[]');
+            $resolver->setAllowedTypes('ports', 'int[]');
         }
     }