Make removing fields easier to understand

Reports like this:

> - Values are no longer limited to the following types:
> 
>     - Array
> 
> - The property was previously explicitly defined. It is now implicitly described by the catch-all "additional properties" case.
> 
> - The property may not be present.

Should probably be "Field probably removed" with a subelement explaining why we think that (the quote above)