doc: clarify use of process.env in worker threads on Windows

Signed-off-by: Daeyeon Jeong <daeyeon.dev@gmail.com>

doc/api/process.md

@@ -1666,7 +1666,9 @@ each [`Worker`][] thread has its own copy of `process.env`, based on its
 parent thread's `process.env`, or whatever was specified as the `env` option
 to the [`Worker`][] constructor. Changes to `process.env` will not be visible
 across [`Worker`][] threads, and only the main thread can make changes that
-are visible to the operating system or to native add-ons.
+are visible to the operating system or to native add-ons. On Windows, a copy of
+`process.env` on a [`Worker`][] instance operates in a case-sensitive manner
+unlike the main thread.
 
 ## `process.execArgv`
 

doc/api/worker_threads.md

@@ -886,7 +886,8 @@ Notable differences inside a Worker environment are:
   unless otherwise specified. Changes to one copy are not visible in other
   threads, and are not visible to native add-ons (unless
   [`worker.SHARE_ENV`][] is passed as the `env` option to the
-  [`Worker`][] constructor).
+  [`Worker`][] constructor). On Windows, unlike the main thread, a copy of the
+  environment variables operates in a case-sensitive manner.
 * [`process.title`][] cannot be modified.
 * Signals are not delivered through [`process.on('...')`][Signals events].
 * Execution may stop at any point as a result of [`worker.terminate()`][]