Add cargo-script RFC to related projects

[tennox]

I guess that's in your interest too?
Or do you see it as not on the same line?

[fornwall]

Thanks! It's indeed related (and https://github.com/epage/cargo-script-mvs started as a fork of this repo).

I think this functionality is great to have built-in to cargo! Once that is in, we can re-think the utility of this project (perhaps it should be offering additional functionality on top that doesn't fit in cargo-script proper, like being able to execute a script given a URL and a checksum).