minor #8076 Update lockable_trait.rst for blocking lock (lpussacq, javiereguiluz)

This PR was merged into the 3.2 branch.

Discussion
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Update lockable_trait.rst for blocking lock

The method lock() of LockableTrait accept 2 parameters, the first one is the name used to create the lock file, and the second is a value indicating if we should wait until the lock is release. Thus, the line $this->lock(true); should be $this->lock('someRandomLockName', true);

Commits
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7c99b93 Use "null" so the lock is named automatically
615817e Update lockable_trait.rst

Author: xabbuh

console/lockable_trait.rst

@@ -30,7 +30,7 @@ that adds two convenient methods to lock and release commands::
             }
 
             // If you prefer to wait until the lock is released, use this:
-            // $this->lock(true);
+            // $this->lock(null, true);
 
             // ...