minor #17769 [HttpKernel] Remove old caution from Symony <4 (BafS)

This PR was merged into the 5.4 branch.

Discussion
----------

[HttpKernel] Remove old caution from Symony <4

<!--

If your pull request fixes a BUG, use the oldest maintained branch that contains
the bug (see https://symfony.com/releases for the list of maintained branches).

If your pull request documents a NEW FEATURE, use the same Symfony branch where
the feature was introduced (and `6.x` for features of unreleased versions).

-->

Commits
-------

9987edd [HttpKernel] Remove old caution from Symony <4

Author: OskarStark

components/http_kernel.rst

@@ -136,13 +136,6 @@ See ":ref:`http-kernel-working-example`" for a more concrete implementation.
 For general information on adding listeners to the events below, see
 :ref:`http-kernel-creating-listener`.
 
-.. caution::
-
-    As of 3.1 the :class:`Symfony\\Component\\HttpKernel\\HttpKernel` accepts a
-    fourth argument, which must be an instance of
-    :class:`Symfony\\Component\\HttpKernel\\Controller\\ArgumentResolverInterface`.
-    In 4.0 this argument will become mandatory.
-
 .. seealso::
 
     There is a wonderful tutorial series on using the HttpKernel component and