Add timoxley, LinusU as contributors

[feross]

I'd like to add @timoxley and @LinusU as GitHub collaborators to standard.

While neither has any commits on the project (as far as the GitHub contributor graph shows), they've both been extremely active and helpful in GitHub issues, testing beta releases, and providing feedback about proposed changes. They feel like part of the core team to me, and they both deeply "get" the philosophy of standard.

I'd like to hear what other collaborators think of this idea. This feels like an appropriate way to recognize useful non-code contributions.

@timoxley @LinusU What do you two say?

[timoxley]

@feross I am honoured. 👍

[LinusU]

I would be honoured as well, thank you 🎉

[feross]

Nice! Just added you to the relevant standard repos on GitHub.