doc: minor edit to worker_threads.md

Change "JS code" to "JavaScript".

PR-URL: nodejs#26870
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/api/worker_threads.md

@@ -4,7 +4,7 @@
 
 > Stability: 1 - Experimental
 
-The `worker_threads` module enables the use of threads that execute JS code
+The `worker_threads` module enables the use of threads that execute JavaScript
 in parallel. To access it:
 
 ```js