[Filesystem] Moved current document to a dedicated folder
[Filesystem] Added documentation for the new LockHandler
feature #3956 [Command] Added LockHelper (lyrixx)

This PR was merged into the master branch.

Discussion
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[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 | -

Commits
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909a294 [Filesystem] Added documentation for the new LockHandler
2bf8c55 [Filesystem] Moved current document to a dedicated folder