minor #4890 Fixed typo (beni0888)

This PR was merged into the 2.3 branch.

Discussion
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Fixed typo

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

Commits
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f1f3c50 Fixed typo

Author: weaverryan

reference/twig_reference.rst

@@ -656,7 +656,7 @@ Global Variables
 app
 ~~~
 
-The ``app`` variable is available everywhere and gives access tomany commonly
+The ``app`` variable is available everywhere and gives access to many commonly
 needed objects and values. It is an instance of
 :class:`Symfony\\Bundle\\FrameworkBundle\\Templating\\GlobalVariables`.