Add pointer to actual YAML in README

[SpencerDawkins]

I am explaining to someone from another SDO what they can/must provide as author information for our draft.

The README.md file has an excellent example with lots of fields, but it's an example. Is there a pointer to the relevant/definitive schema that could be added as well, so we can verify what's actually possible?

[cabo]

Clearly, adding a data definition ("schema") would be useful, so people could validate their YAML. Keeping this issue as a todo.
The fun part will be the interaction with rfcXML, as some of the data kramdown-rfc accepts will then not be acceptable to xml2rfc (and only part of this is covered by the Relax-NG grammar for RFCXML). Until that work is done, the Wiki also has useful information...