minor #5160 Update process.rst (sfdumi)

This PR was merged into the 2.3 branch.

Discussion
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Update process.rst

Corrected verb form.

Commits
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22ff64d Update process.rst

components/process.rst

@@ -40,7 +40,7 @@ when executing the command.
     The ``getIncrementalOutput()`` and ``getIncrementalErrorOutput()`` methods
     were introduced in Symfony 2.2.
 
-The ``getOutput()`` method always return the whole content of the standard
+The ``getOutput()`` method always returns the whole content of the standard
 output of the command and ``getErrorOutput()`` the content of the error
 output. Alternatively, the :method:`Symfony\\Component\\Process\\Process::getIncrementalOutput`
 and :method:`Symfony\\Component\\Process\\Process::getIncrementalErrorOutput`