Show how to configure lifetime for app.cache.

This will fix symfony#10988

Author: Nyholm

cache.rst

@@ -250,6 +250,7 @@ For advanced configurations it could sometimes be useful to use a pool as an ada
  # config/packages/cache.yaml
  framework:
  cache:
+ app: my_configured_app_cache
  pools:
  my_cache_pool:
  adapter: cache.adapter.memcached
@@ -260,6 +261,10 @@ For advanced configurations it could sometimes be useful to use a pool as an ada
  cache.long_cache:
  adapter: my_cache_pool
  default_lifetime: 604800
+ my_configured_app_cache:
+ # "cache.adapter.filesystem" is the default for "cache.app"
+ adapter: cache.adapter.filesystem
+ default_lifetime: 3600
 
  .. code-block:: xml
 
@@ -272,10 +277,12 @@ For advanced configurations it could sometimes be useful to use a pool as an ada
  https://symfony.com/schema/dic/services/services-1.0.xsd">
 
  <framework:config>
- <framework:cache>
+ <framework:cache app="my_cache_pool">
  <framework:pool name="my_cache_pool" adapter="cache.adapter.memcached" provider="memcached://user:password@example.com"/>
  <framework:pool name="cache.short_cache" adapter="my_cache_pool" default_lifetime="604800"/>
  <framework:pool name="cache.long_cache" adapter="my_cache_pool" default_lifetime="604800"/>
+ <!-- "cache.adapter.filesystem" is the default for "cache.app" -->
+ <framework:pool name="my_configured_app_cache" adapter="cache.adapter.filesystem" default_lifetime="3600"/>
  </framework:cache>
  </framework:config>
  </container>
@@ -285,6 +292,7 @@ For advanced configurations it could sometimes be useful to use a pool as an ada
  // config/packages/cache.php
  $container->loadFromExtension('framework', [
  'cache' => [
+ 'app' => 'my_configured_app_cache',
  'pools' => [
  'my_cache_pool' => [
  'adapter' => 'cache.adapter.memcached',
@@ -298,6 +306,11 @@ For advanced configurations it could sometimes be useful to use a pool as an ada
  'adapter' => 'cache.adapter.memcached',
  'default_lifetime' => 604800,
  ],
+ 'my_configured_app_cache' => [
+ // "cache.adapter.filesystem" is the default for "cache.app"
+ 'adapter' => 'cache.adapter.filesystem',
+ 'default_lifetime' => 3600,
+ ],
  ],
  ],
  ]);