minor #18796 [Lock] Blocking locks example (simoheinonen)

This PR was merged into the 5.4 branch.

Discussion
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[Lock] Blocking locks example

Redis store doesn't support blocking so doesn't make sense to use it as an example

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Commits
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dbb7f85 Update lock.rst

Author: javiereguiluz

components/lock.rst

@@ -145,9 +145,9 @@ pass ``true`` as the argument of the ``acquire()`` method. This is called a
 lock is acquired::
 
     use Symfony\Component\Lock\LockFactory;
-    use Symfony\Component\Lock\Store\RedisStore;
+    use Symfony\Component\Lock\Store\FlockStore;
 
-    $store = new RedisStore(new \Predis\Client('tcp://localhost:6379'));
+    $store = new FlockStore('/var/stores');
     $factory = new LockFactory($store);
 
     $lock = $factory->createLock('pdf-creation');