feature #19399 [FrameworkBundle] Update cache_dir config (Okhoshi)

This PR was merged into the 7.1 branch.

Discussion
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[FrameworkBundle] Update `cache_dir` config

Update the documentation on configuration of the FrameworkBundle to reflect the deprecation of `cache_dir` (done in symfony/symfony#52962) and the introduction of `ignore_cache` (from symfony/symfony#53059).

Fixes #19281

Ping `@alexandre`-daubois

Commits
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47e0be0 [FrameworkBundle] Update cache_dir config

Author: OskarStark

reference/configuration/framework.rst

@@ -1511,6 +1511,19 @@ cache_dir
 The directory where routing information will be cached. Can be set to
 ``~`` (``null``) to disable route caching.
 
+.. deprecated:: 7.1
+
+    Setting the ``cache_dir`` option is deprecated since Symfony 7.1. The routes
+    are now always cached in the ``%kernel.build_dir%`` directory. If you want
+    to disable route caching, set the ``ignore_cache`` option to ``true``.
+
+ignore_cache
+............
+
+**type**: ``boolean`` **default**: ``false``
+
+When this option is set to ``true``, routing information will not be cached.
+
 secrets
 ~~~~~~~