minor #7790 Update dialoghelper.rst (adpauly)

This PR was submitted for the 2.3 branch but it was merged into the 2.7 branch instead (closes #7790).

Discussion
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Update dialoghelper.rst

Typo: removed "s".

Commits
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d23153f Update dialoghelper.rst

Author: xabbuh

components/console/helpers/dialoghelper.rst

@@ -125,7 +125,7 @@ method::
         'AcmeDemoBundle'
     );
 
-This methods has 2 new arguments, the full signature is::
+This method has 2 new arguments, the full signature is::
 
     askAndValidate(
         OutputInterface $output,