minor #1622 Remove typo (tcitworld)

This PR was merged into the 2.3.x-dev branch.

Discussion
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Remove typo

Remove extra parenthesis

Commits
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8781803b Remove typo

doc/providers/form.rst

@@ -157,7 +157,7 @@ You can register form types by extending ``form.types``::
         $types[] = 'your.type.service';
 
         return $types;
-    }));
+    });
 
 You can register form extensions by extending ``form.extensions``::