Update cache.rst

Co-authored-by: Oskar Stark <[email protected]>

Author: bobvandevijver

cache.rst

@@ -726,8 +726,9 @@ 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
+        $ php bin/console cache:pool:clear --all
 
 .. versionadded:: 6.3