minor symfony#14271 Fix typo (jdreesen)

This PR was merged into the 3.4 branch.

Discussion
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Fix typo

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Commits
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9fdc8dc Fix typo

bundles/configuration.rst

@@ -370,7 +370,7 @@ In XML, the `XML namespace`_ is used to determine which elements belong to the
 configuration of a specific bundle. The namespace is returned from the
 :method:`Extension::getNamespace() <Symfony\\Component\\DependencyInjection\\Extension\\Extension::getNamespace>`
 method. By convention, the namespace is a URL (it doesn't have to be a valid
-URL nor does it need to exists). By default, the namespace for a bundle is
+URL nor does it need to exist). By default, the namespace for a bundle is
 ``http://example.org/schema/dic/DI_ALIAS``, where ``DI_ALIAS`` is the DI alias of
 the extension. You might want to change this to a more professional URL::