doc: simplify copy-pasting of branch-diff commands

PR-URL: nodejs#52757
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

doc/contributing/releases.md

@@ -185,7 +185,7 @@ duplicate or not.
 For a list of commits that could be landed in a minor release on v1.x:
 
 ```bash
-branch-diff v1.x-staging main --exclude-label=semver-major,dont-land-on-v1.x,backport-requested-v1.x,backport-blocked-v1.x,backport-open-v1.x,backported-to-v1.x --filter-release --format=simple
+N=1 sh -c 'branch-diff v$N.x-staging upstream/main --exclude-label=semver-major,dont-land-on-v$N.x,backport-requested-v$N.x,backport-blocked-v$N.x,backport-open-v$N.x,backported-to-v$N.x --filter-release --format=simple'
 ```
 
 Previously released commits and version bumps do not need to be
@@ -204,7 +204,7 @@ When you are ready to cherry-pick commits, you can automate with the following
 command.
 
 ```bash
-branch-diff v1.x-staging main --exclude-label=semver-major,dont-land-on-v1.x,backport-requested-v1.x,backport-blocked-v1.x,backport-open-v1.x,backported-to-v1.x --filter-release --format=sha --reverse | xargs git cherry-pick
+N=1 sh -c 'branch-diff v$N.x-staging upstream/main --exclude-label=semver-major,dont-land-on-v$N.x,backport-requested-v$N.x,backport-blocked-v$N.x,backport-open-v$N.x,backported-to-v$N.x --filter-release --format=sha --reverse' | xargs git cherry-pick -S
 ```
 
 <sup>For patch releases, make sure to add the `semver-minor` tag