[Command] Added LockHelper

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes https://github.com/symfony/symfony/pull/10475
| Applies to    | Symfony version 2.6+
| Fixed tickets | -
I would remove the part after `and` (that's great for a blog post, but bad for a documentation article). I would say something like "Symfony provides a LockHelper to help you using the lock mechanism in your projects."