Put ghstack message below commit message body / update local message with remote about ghstack

[ezyang]

I was wondering if there is a (technical) reason that the ghstack info is inserted above the commit message?

There is no technical reason. An aesthetic reason for placing it up top is when you navigate between PRs, the stack list stays at a fixed position (like a menubar). If you want to add a config to toggle it, I guess it's OK; it doesn't seem like the payoff is that great though, but it's pretty simple.

And I was curious if amending the local commit message with remote changes has come up in the past? The use case here is that I/we often add screenshots to a commit on github.com directly. When I update the commit by running ghstack again, the remote edits are overwritten.

Ah yes, this should exist as a feature, it just hasn't been written. Please implement it as ghstack sync [--stack] (stack argument to update all commits in your stack).

[ezyang]

Duping it as #67