Think about developer documentation

[JoeZiminski]

There are a number of soft conventions maintained in the codebase. These aren't super strict but it would be nice to have them somewhere, most likely in the contributing.md documentation. For now, these feel a bit like a random list, so we might want to wait to pad this out until adding them to the documentation. At some point, the form may be dedicated, detailed developer documentation that dives deeper into the codebase, rather than a more general high-level contributing guide.

[JoeZiminski]

• doc that await pilot.pause() is required at end of all tui tests.
• doc exactly how SSH, GDrive and AWS tests work
• doc how backward compatability tests work
• just a convention in the codebase, the caller function is generally above the called function)