minor #6786 Subject-verb agreement (micheal)

This PR was submitted for the 3.1 branch but it was merged into the 2.7 branch instead (closes #6786).

Discussion
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Subject-verb agreement

Commits
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b8240c9 Subject-verb agreement

Author: weaverryan

controller/upload_file.rst

@@ -422,7 +422,7 @@ Now, register this class as a Doctrine listener:
         ));
         $container->setDefinition('app.doctrine_brochure_listener', $definition);
 
-This listeners is now automatically executed when persisting a new Product
+This listener is now automatically executed when persisting a new Product
 entity. This way, you can remove everything related to uploading from the
 controller.