workqueue: Comment correction in file header

 *

 * This is the generic async execution mechanism.  Work items as are

 * executed in process context.  The worker pool is shared and

 * automatically managed.  There is one worker pool for each CPU and

 * one extra for works which are better served by workers which are

 * not bound to any specific CPU.

 * automatically managed.  There are two worker pools for each CPU (one for

 * normal work items and the other for high priority ones) and some extra

 * pools for workqueues which are not bound to any specific CPU - the

 * number of these backing pools is dynamic.

 *

 * Please read Documentation/workqueue.txt for details.

 */