meta: document commit msg exception for long URLs

PR-URL: #20207
Fixes: #17116
Refs: nodejs/core-validate-commit#24
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>

doc/guides/contributing/pull-requests.md

@@ -151,7 +151,7 @@ A good commit message should describe what changed and why.
 
 
 2. Keep the second line blank.
-3. Wrap all other lines at 72 columns.
+3. Wrap all other lines at 72 columns (except for long URLs).
 
 4. If your patch fixes an open issue, you can add a reference to it at the end
 of the log. Use the `Fixes:` prefix and the full issue URL. For other references