Improve process for creating browser support guidelines

[sebworks]

There currently isn't a set of official standards or guidelines outlining the which browsers we support and why we support them.

We should create a browser support matrix, which provides clear guidelines on which browsers we support and why. This might entail a no-js experience, browser support notifications, and / or a basic fallback experience.

Regardless of browser or JS, all critical information should be accessible to the users.