I have signed the copyright assignment before.

The change is very small, so I think taking a look at the diff is more informative than I trying to explain it; the old code did not use `org-link-make-description-function` when some other alternatives were available, but my changes make it always use `org-link-make-description-function` if set.

This change is a breaking API change, but I think the previous behavior was a bug. If you want to preserve the old behavior, perhaps we should add a new variable `org-link-postprocess-description-function`?

Changelog: