doc: improve module.builtinModules text

`module is maintained by a third-party module` seems confusing. Changed
to `module is maintained by a third-party`.

PR-URL: #17865
Reviewed-By: Weijia Wang <starkwang@126.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/modules.md

@@ -839,7 +839,7 @@ added: v9.3.0
 * {string[]}
 
 A list of the names of all modules provided by Node.js. Can be used to verify
-if a module is maintained by a third-party module or not.
+if a module is maintained by a third party or not.
 
 Note that `module` in this context isn't the same object that's provided
 by the [module wrapper][]. To access it, require the `Module` module: