minor #18072 [Cache] Add documentation for new --all option for cache:pool:clear (bobvandevijver)

This PR was squashed before being merged into the 6.3 branch.

Discussion
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[Cache] Add documentation for new `--all` option for `cache:pool:clear`

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Documentation update for symfony/symfony#49705.

Commits
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bb7796d [Cache] Add documentation for new `--all` option for `cache:pool:clear`

Author: javiereguiluz

cache.rst

@@ -722,6 +722,15 @@ Clear all custom pools:
 
     $ php bin/console cache:pool:clear cache.app_clearer
 
+Clear all cache pools:
+    .. code-block:: terminal
+
+        $ php bin/console cache:pool:clear --all
+
+.. versionadded:: 6.3
+
+    The `--all` option was introduced in Symfony 6.3.
+
 Clear all caches everywhere:
 
 .. code-block:: terminal