minor symfony#9940 Updated the default values of some Cache config options (javiereguiluz)

This PR was merged into the 3.4 branch.

Discussion
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Updated the default values of some Cache config options

This error was originally spotted by @Majkl578 and the solution verified by @ostrolucky on Symfony Slack.

Commits
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58a5d25 Updated the default values of some Cache config options

Author: javiereguiluz

reference/configuration/framework.rst

@@ -2117,8 +2117,8 @@ Full Default Configuration
 
             # cache configuration
             cache:
-                app: cache.app
-                system: cache.system
+                app: cache.adapter.filesystem
+                system: cache.adapter.system
                 directory: '%kernel.cache_dir%/pools'
                 default_doctrine_provider: ~
                 default_psr6_provider: ~