Address Early Adpoter's feedback

This PR addresses all of the points in the feedback as discussed in #8, for @honzajavorek to review & merge
@honzajavorek I think you are grappling with the `One of` here – let me rephrase it: 

One of is an array of elements. Each of this element is mutually exclusive with another. One of this element may be an group (collection) of elements (that are not mutually exclusive!). 

```
- one of
   - full_name
   - properities
        - first
        - last
```