minor #3923 Fixed the headers of one table (javiereguiluz)

This PR was merged into the 2.4 branch.

Discussion
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Fixed the headers of one table

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.4+
| Fixed tickets | -

Commits
-------

864d930 Fixed the headers of one table

components/http_kernel/introduction.rst

@@ -571,7 +571,7 @@ each event has their own event object:
 
 +-----------------------+----------------------------------+-------------------------------------------------------------------------------------+
 | Name                  | ``KernelEvents`` Constant        | Argument passed to the listener                                                     |
-+-----------------------+----------------------------------+-------------------------------------------------------------------------------------+
++=======================+==================================+=====================================================================================+
 | kernel.request        | ``KernelEvents::REQUEST``        | :class:`Symfony\\Component\\HttpKernel\\Event\\GetResponseEvent`                    |
 +-----------------------+----------------------------------+-------------------------------------------------------------------------------------+
 | kernel.controller     | ``KernelEvents::CONTROLLER``     | :class:`Symfony\\Component\\HttpKernel\\Event\\FilterControllerEvent`               |