bug symfony#11557 Typo (sylfabre)

This PR was submitted for the 4.2 branch but it was merged into the 3.4 branch instead (closes symfony#11557).

Discussion
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Typo

According to https://symfony.com/doc/current/components/yaml/yaml_format.html#collections, mappings uses `{ }` instead of `[ ]`

Commits
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6b0b76a Typo

Author: wouterj

cache.rst

@@ -345,7 +345,7 @@ and use that when configuring the pool.
                 factory: ['Symfony\Component\Cache\Adapter\RedisAdapter', 'createConnection']
                 arguments:
                     - 'redis://localhost'
-                    - [ retry_interval: 2, timeout: 10 ]
+                    - { retry_interval: 2, timeout: 10 }
 
     .. code-block:: xml