Added the new documentation inside a "caution" admonition

Author: javiereguiluz

components/filesystem/lock_handler.rst

@@ -62,23 +62,25 @@ You can pass an optional blocking argument as the first argument to the
 ``lock()`` method, which defaults to ``false``. If this is set to ``true``, your
 PHP code will wait indefinitely until the lock is released by another process.
 
-Beware that the resource lock is automatically released as soon as PHP applies the
-garbage-collection process to the ``LockHandler`` object. This means that if you
-refactor the first example showed in this article as follows:
+.. caution::
 
-.. code-block:: php
+    Beware that the resource lock is automatically released as soon as PHP applies
+    the garbage-collection process to the ``LockHandler`` object. This means that
+    if you refactor the first example showed in this article as follows:
 
-    use Symfony\Component\Filesystem\LockHandler;
+    .. code-block:: php
 
-     if (!(new LockHandler('hello.lock'))->lock()) {
-        // the resource "hello" is already locked by another process
+        use Symfony\Component\Filesystem\LockHandler;
 
-        return 0;
-    }
+         if (!(new LockHandler('hello.lock'))->lock()) {
+            // the resource "hello" is already locked by another process
+
+            return 0;
+        }
 
-Now the code won't work as expected, because PHP's garbage collection mechanism
-removes the reference to the ``LockHandler`` object and thus, the lock is released
-just after it's been created.
+    Now the code won't work as expected, because PHP's garbage collection mechanism
+    removes the reference to the ``LockHandler`` object and thus, the lock is released
+    just after it's been created.
 
-Another alternative way to release the lock explicitly when needed is to use the
-:method:`Symfony\\Component\\Filesystem\\LockHandler::release` method.
+    Another alternative way to release the lock explicitly when needed is to use the
+    :method:`Symfony\\Component\\Filesystem\\LockHandler::release` method.