oc: fix duplicate word "of of" in postMessageToThread

Author: watilde

doc/api/worker_threads.md

@@ -513,7 +513,7 @@ parent or child of the current thread.
 If the two threads are parent-children, use the [`require('node:worker_threads').parentPort.postMessage()`][]
 and the [`worker.postMessage()`][] to let the threads communicate.
 
-The example below shows the use of of `postMessageToThread`: it creates 10 nested threads,
+The example below shows the use of `postMessageToThread`: it creates 10 nested threads,
 the last one will try to communicate with the main thread.
 
 ```mjs