minor #5678 Update HttpFoundation note after recent changes in routing component (senkal)

This PR was squashed before being merged into the 2.3 branch (closes #5678).

Discussion
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Update HttpFoundation note after recent changes in routing component

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3
| Fixed tickets |

Update HttpFoundation note to reflect changes in #5652.
We do not longer use `$_SERVER['REQUEST_URI']` in examples so keeping the reference in note doesn't have much value.
I updated it to make it more generic and reflect current examples.

Commits
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36234f2 Update HttpFoundation note after recent changes in routing component

Author: xabbuh

components/routing/introduction.rst

@@ -48,10 +48,9 @@ your autoloader to load the Routing component::
 
 .. note::
 
-    Be careful when using ``$_SERVER['REQUEST_URI']``, as it may include
-    any query parameters on the URL, which will cause problems with route
-    matching. An easy way to solve this is to use the HttpFoundation component
-    as explained :ref:`below <components-routing-http-foundation>`.
+    The :class:`Symfony\\Component\\Routing\\RequestContext` parameters can be populated
+    with the values stored in ``$_SERVER``, but it's easier to use the HttpFoundation
+    component as explained :ref:`below <components-routing-http-foundation>`.
 
 You can add as many routes as you like to a
 :class:`Symfony\\Component\\Routing\\RouteCollection`.