Add draft of Metaspec.

[lthibault]

The Metaspec is a specification for SUAVE specifications. It aims to add Just Enough (TM) structure to our prose to facilitate automated conformance testing and rendering pipelines in the future.

This is the first step in my effort to overhaul our specs, and feedback is warmly welcomed.

[lthibault]

Here's a quick render to show you what it looks like

[lthibault]

Addendum: this is a quick-and-dirty draft aimed to get something out the door. It's probably a good idea to explicitly define each state in the lifecycle and list the corresponding criteria. I can do that in a separate PR -- just want to get early feedback before going too deep.

[metachris]

I see it's adding a metaspec directory, what's the purpose there instead of just putting the metaspec in the root as markdown file?

could also link ethereum specs as inspiration.

[metachris]

(whoops sorry, misclicked and closed by accident)