[#6690] fix syntax error

Author: xabbuh

components/console/introduction.rst

@@ -233,7 +233,7 @@ level. For example::
     $output->writeln('...', OutputInterface::VERBOSITY_VERBOSE);
 
 .. versionadded:: 2.8
-    The ability to pass the verbosity level to the ``writeln()` method was
+    The ability to pass the verbosity level to the ``writeln()`` method was
     introduced in Symfony 2.8.
 
 There are also more semantic methods you can use to test for each of the