minor #15408 [Configuration] Update front_controllers_and_kernel.rst (a-menshchikov)

This PR was merged into the 5.2 branch.

Discussion
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[Configuration] Update front_controllers_and_kernel.rst

UrlGenerator.php and UrlMatcher.php were deprecated and changed in Symfony 5.

Commits
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e4e7f1d Update front_controllers_and_kernel.rst

Author: javiereguiluz

configuration/front_controllers_and_kernel.rst

@@ -248,13 +248,12 @@ includes the following:
     The cached "service container" that represents the cached application
     configuration.
 
-``UrlGenerator.php``
-    The PHP class generated from the routing configuration and used when
-    generating URLs.
+``url_generating_routes.php``
+    The cached routing configuration that used when generating URLs.
 
-``UrlMatcher.php``
-    The PHP class used for route matching - look here to see the compiled regular
-    expression logic used to match incoming URLs to different routes.
+``url_matching_routes.php``
+    The cached configuration used for route matching - look here to see the compiled
+    regular expression logic used to match incoming URLs to different routes.
 
 ``twig/``
     This directory contains all the cached Twig templates.