doc,worker: revise worker_threads.md

Rewrite worker_threads introductory material focusing on simpler and
shorter sentences.

PR-URL: https://github.com/nodejs/node/pull/25402
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Eugene Ostroukhov <eostroukhov@google.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

doc/api/worker_threads.md

@@ -4,21 +4,20 @@
 
 > Stability: 1 - Experimental
 
-The `worker` module provides a way to create multiple environments running
+The `worker_threads` module enables the use of threads with message channels
-on independent threads, and to create message channels between them. It
+between them. To access it:
-can be accessed using:
 
 ```js
 const worker = require('worker_threads');
 ```
 
-Workers are useful for performing CPU-intensive JavaScript operations; do not
+Workers (threads) are useful for performing CPU-intensive JavaScript operations.
-use them for I/O, since Node.js’s built-in mechanisms for performing operations
+They will not help much with I/O-intensive work. Node.js’s built-in asynchronous
-asynchronously already treat it more efficiently than Worker threads can.
+I/O operations are more efficient than Workers can be.
 
-Workers, unlike child processes or when using the `cluster` module, can also
+Unlike `child_process` or `cluster`, `worker_threads` can share memory. They do
-share memory efficiently by transferring `ArrayBuffer` instances or sharing
+so by transferring `ArrayBuffer` instances or sharing `SharedArrayBuffer`
-`SharedArrayBuffer` instances between them.
+instances.
 
 ```js
 const {
@@ -46,10 +45,9 @@ if (isMainThread) {
 }
 ```
 
-Note that this example spawns a Worker thread for each `parse` call.
+The above example spawns a Worker thread for each `parse()` call. In actual
-In practice, it is strongly recommended to use a pool of Workers for these
+practice, use a pool of Workers instead for these kinds of tasks. Otherwise, the
-kinds of tasks, since the overhead of creating Workers would likely exceed the
+overhead of creating Workers would likely exceed their benefit.
-benefit of handing the work off to it.
 
 ## worker.isMainThread
 <!-- YAML