doc: update README to make Node.js description clearer

Fixes: nodejs#24872

PR-URL: nodejs#31266
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Rich Trott <rtrott@gmail.com>

README.md

@@ -8,8 +8,9 @@
   </a>
 </p>
 
-Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine. For
-more information on using Node.js, see the [Node.js Website][].
+Node.js is an open-source, cross-platform, JavaScript runtime environment. It
+executes JavaScript code outside of a browser. For more information on using
+Node.js, see the [Node.js Website][].
 
 The Node.js project uses an [open governance model](./GOVERNANCE.md). The
 [OpenJS Foundation][] provides support for the project.