Provide RML-FNML translation for conditions

[dachafra]

The current spec provides for each example a translation from YARRRML to the corresponding mapping in RML.
The conditions is the only section where this translation is not provided.

I've used Matey to see an example of the output but considering we have a new RML-FNML specification it would be great to know if it covers the requirements for the conditions (as I saw in Matey's output, I think currently it's purely supported by FNML) or we would also need to update the core spec to explicitly add the conditions.