List the parts of joi API we can handle

There are lots of api features. We will need to be clear which features we can handle on both the front end and back.

Some will cause errors whilst others will work just fine but have no real effect on the database or front end at least.

As a developer implements a features they should add it to the subset of API we can handle.
- [ ] Create markdown table detailing any feature handled and its effect on both backend and front end.