doc: update documentation for externalizing deps

Refs: https://github.com/nodejs/node/pull/54646

- Add instructions to update how process.versions is reported
  as I missed that in a recent addition.

Signed-off-by: Michael Dawson <midawson@redhat.com>
PR-URL: https://github.com/nodejs/node/pull/54792
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Akhil Marsonya <akhil.marsonya27@gmail.com>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>

doc/contributing/maintaining/maintaining-dependencies.md

@@ -126,6 +126,17 @@ can be added by:
   paste one of the existing entries and then update to match the
   import name for the dependency and the #define generated.
 
+* if the version of the dependency is reported in `process.versions`,
+  update `src/node_metadata.h` and `src/node_metadata.cc` so that the
+  version is not reported when the dependency is externalized.
+  Not reporting the version is better than incorrectly reporting
+  the version of the dependency bundled with Node.js, instead of the
+  version for the externalized dependency. Use one of the existing
+  externalized dependencies, like Undici, as an example of how to
+  update these files correctly. Make sure to run the tests with the
+  dependency externalized, as the tests will also need to be updated
+  to handle this properly.
+
 ## Supporting non-externalized dependencies with JavaScript code
 
 If the dependency consists of JavaScript in the