Clarify whether packaging should be done locally or on sandstorm server via ssh connection

[neuroradiology]

It's not clear to me from the documentation whether I should be performing the packaging on my local dev box, or on the server.

I'm 90% sure it's on my local machine because the documentation talks about compatibility with Windows and Mac OS, but I think this is worth stating explicitly in the README of entire repo.

I'm happy to generate a pull request along these lines, but first I want to make sure my understanding is correct and that it would be welcome.

Massive props to the sandstorm team; this project is just incredibly cool.

[ocdtrekkie]

vagrant-spk is self-contained, it installs a Sandstorm server inside the virtual machine it creates for developing your app, and any commands which need Sandstorm to do are directed to use that server.

Sometimes our docs can lead you down different paths because there are different ways to package apps. For instance, the plain spk tool would be used to do development and packaging on a server which has Sandstorm installed.

PRs are indeed very welcome on both the vagrant-spk repo and the main sandstorm repo which contains our documentation!

[zenhack]

Your understanding is correct; any command involving vagrant-spk should be run on the host machine, not the guest.