doc: fix invalid link in worker_threads.md

Inadvertent double hash in link makes it invalid and no longer pointing
to the documentation section it intends to point to.

PR-URL: #36109
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>

Author: Trott

doc/api/worker_threads.md

@@ -987,7 +987,7 @@ active handle in the event system. If the worker is already `unref()`ed calling
 [`fs.close()`]: fs.md#fs_fs_close_fd_callback
 [`fs.open()`]: fs.md#fs_fs_open_path_flags_mode_callback
 [`markAsUntransferable()`]: #worker_threads_worker_markasuntransferable_object
-[`perf_hooks.performance`]: #perf_hooks.md#perf_hooks_perf_hooks_performance
+[`perf_hooks.performance`]: perf_hooks.md#perf_hooks_perf_hooks_performance
 [`perf_hooks` `eventLoopUtilization()`]: perf_hooks.md#perf_hooks_performance_eventlooputilization_utilization1_utilization2
 [`port.on('message')`]: #worker_threads_event_message
 [`port.onmessage()`]: https://developer.mozilla.org/en-US/docs/Web/API/MessagePort/onmessage