Doc thread_handling is not complete

In the server variables configuration thread_handling for Windows is not documented completely:

https://mariadb.com/kb/en/thread-pool-system-status-variables/#thread_handling

On modern Windows systems thread_handling is set by default to pool-of-threads as stated here:

"On Windows, if you would like to use the thread pool, then you do not need to do anything, because the default for the thread_handling system variable is already preset to pool-of-threads."

https://mariadb.com/kb/en/thread-pool-in-mariadb/#configuring-the-thread-pool-on-windows

This is missing in the variables overview.