Improve `--allow-update-branch` flag description of the `repo edit` command

### Describe the feature or problem you’d like to solve

There are repo settings which can be set via the web interface, but not using `gh repo edit`. The ones I've noticed are ...

* "Always suggest updating PR branches" ... this *might be* the same as `--allow-update-branch`, but the descriptions aren't clear. If nothing else, it may be worth ensuring that the descriptions given by `gh help repo edit` tell which options in the web interface they correspond to, or maybe use the exact same wording in both places.

* "Include git-lfs objects in archives" ... I don't see anything in the source code which mentions

### Proposed solution

* Add options so that `gh repo edit` can be used to do anything that can be done using the web interface.

* Update descriptions to that users can tell which command line options correspond to which web interface options.

* Added bonus: add an option which shows the underlying API calls that the `gh` command is making. This could also be combined with a "no-op" option, so people can *see* the API calls without actually *calling* them. This could be a huge help for people writing their own scripts which call the APIs directly, rather than spawning shells to run `gh` commands.