doc: add note about shasum generation failure

PR-URL: #54487
Reviewed-By: Ulises Gascón <ulisesgascongonzalez@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: marco-ippolito

doc/contributing/releases.md

@@ -944,6 +944,13 @@ a `NODEJS_RELEASE_HOST` environment variable:
 NODEJS_RELEASE_HOST=proxy.xyz ./tools/release.sh
 ```
 
+> \[!TIP]
+> Sometimes, due to machines being overloaded or other external factors,
+> the files at <https://nodejs.org/dist/index.json>, <https://nodejs.org/dist/index.tab>
+> or `SHASUMS256.txt` may not be generated correctly.
+> In this case you can repeat the signing step in order
+> to fix it. e.g: `./tools/release.sh -s`.
+
 `tools/release.sh` will perform the following actions when run:
 
 <details>