minor #12349 Additional help with Real-Time Output (JWPapi)

This PR was submitted for the 4.3 branch but it was merged into the 3.4 branch instead (closes #12349).

Discussion
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Additional help with Real-Time Output

I have seen quite some issuse and questions. I think its quite common that php.ini is not allowing real-time output. So the hint helps probably some people

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Commits
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a7b38c8 Additional help with Real-Time Output

Author: javiereguiluz

components/process.rst

@@ -41,7 +41,7 @@ when executing the command.
 
 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`
+output.Alternatively, the :method:`Symfony\\Component\\Process\\Process::getIncrementalOutput`
 and :method:`Symfony\\Component\\Process\\Process::getIncrementalErrorOutput`
 methods return the new output since the last call.
 
@@ -152,6 +152,8 @@ anonymous function to the
         }
     });
 
+If this is not working, it can be that your server has an output buffer, that means your Server is not giving the information to the browser, so Symfony can't display it. You can use ``ob_flush()`` and ``flush()`` in combination with ``sleep()`` to avoid this in this process. Or change ``output_buffering`` in php.ini to change it globally.
+
 Running Processes Asynchronously
 --------------------------------