Currently, the "Diff Detail" section for a Differential revision shows the name of the feature branch that the revision was created from, but doesn't show any information about what branch the author intends to land the revision onto.
This information would be nice to show, for cases where there are multiple active "release" branches—e.g. a "1.0" and "master" branch, so that reviewers have the right context in mind when reviewing the change. For example, if the revision uses an API that was deprecated in master but not in 1.0, the reviewer would only want to add a comment to that effect if the change is targeted at master.
A helpful default for this "targeted" branch would be the branch that the feature branch is tracking, which is also nicely consistent with the default value for `--onto` in `arc land`. It'd also be useful to be able to specify the targeted branch explicitly, for cases where the feature branch isn't tracking another branch for some reason or the tracking branch isn't where it will be landed.