Update README.md

[JanX2]

The README was omitting the fact that xctool is a requirement for building Rebel.

[dannygreg]

This step should probably just be added to script/bootstrap rather than documenting it.

[jspahrsummers]

@JanX2 Since the bootstrap script will explain the issue, will this change to the README actually be more helpful?

@dannygreg I don't think a bootstrap script on a random OSS project should install things via Homebrew. That should be up to the user, to install in whatever manner they choose.

[dannygreg]

I don't think a bootstrap script on a random OSS project should install things via Homebrew.

Isn't it's purpose to install dependencies though?

[jwilling]

For what it's worth, is xctool really needed at all, if it's only used to pull down dependencies? I don't know much about how this bootstrap works (so feel free to ignore this comment), but I've always thought it odd that it needs a third-party build tool to do the job.

[jspahrsummers]

@dannygreg The bootstrap script is meant to initialize the project and install local dependencies as required. I think we'd be a Bad Citizen™ to install something system-wide in script/bootstrap (especially because we tell everyone to run it after cloning).

@jwilling makes a good point too. xctool is really just for the cibuild script. It probably shouldn't even be mentioned in bootstrap.

[mdiep]

This seems stale.