doc: add missing copyFile change history

[codebytere]

Discovered when working to upgrade Electron to Node.js v14.x - the changes in #27044 were semver-major and thus should likely be added into the change history for those methods.

cc @BridgeAR

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• documentation is changed or added
• commit message follows commit guidelines

[mscdex]

It's debatable that this is worth including, especially considering the semver-major label of the original PR was added "defensively" as the PR was designed to fix a bug.

I don't think we typically document these sorts of changes to APIs (?) because users should have been passing legitimate values in the first place.

[codebytere]

@mscdex i don't feel terribly strongly about the name change i suppose, but i think it's helpful for users who may wonder why references to a parameter have changed. In the interest of ensuring that the barriers to effective documentation grokking remain low, i think there is value in minimizing potential sources of confusion.

[Trott]

I don't mind erring on the side of over-communicating in the change-logging YAML stuff, especially since the material is hidden by default in the rendered HTML docs.

[codebytere]

Landed in 06212bd