New Foundational Discussion Repo for AR

Hello, immersive web folks.

After discussion in this thread
<https://github.com/immersive-web/proposals/issues/51> and in consideration
of how we're now using feature incubation and API module repos, I've
created a new repository for discussion and documentation of cross-API
aspects of augmented reality: https://github.com/immersive-web/ar-common

This repo is for a similar purpose to the privacy-and-security repo
<https://github.com/immersive-web/privacy-and-security> in that it's not
for working out IDL or similarly specific aspects of an API but is instead
a place to discuss foundational aspects of AR in more detail than a single
Issue in the proposals repo allows.

As always, let me know if you have any questions about how to use this or
any other repo.

- Trevor

-- 

*Trevor Flowers* 🌸🌸
trevor@transmutable.com
Principal at Transmutable <https://transmutable.com/>
Friend of the Wider Web <https://potassiumes.org/wider-web/>