Backport instructions unclear how metadata is added #61955

For releasers, can you prepend Backport-PR-URL: https://github.com/nodejs/node/pull/61840 to your commit trailers?

That's actually discouraged, it's preferable to keep the commit message as is, the tooling will add the correct metadata

Originally posted by @aduh95 in #61840 (comment)

https://github.com/nodejs/node/blob/main/doc/contributing/backporting-to-release-lines.md#manual-process includes the text:

Leave the commit message as is. If you think it should be modified, comment in the pull request. The Backport-PR-URL metadata does need to be added to the commit, but this will be done later.

Based on the above feedback, this could benefit from clarification.

Perhaps something like the following? ...

The Backport-PR-URL metadata does need to be added to the commit and this will be done automatically later by tooling. Do not add this metadata manually to the commit.