Fix: #10. Add YAML interoperability/security considerations.

[ioggstream]

This PR

• adds yaml security considerations
• YAML not more JSON superset, but "flow style can resemble JSON"
• mention old yaml versions

Note

• todo: add normative statements wrt using yaml as a more concise form for describing json objects

[ioggstream]

Thanks @ingydotnet for your review.

The issues should probably only be discussed in the abstract.

I made them more abstract, but since the text is for a broad audience of yaml users, I think it is useful to provide some background.

Also YAML is a versioned language that changes over time, so how will the mediatype account for that?

This is the same for every language: when JSON RFC was updated, the media type registration note was changed too. When the language change, the media type can be updated. You do not necessarily require an RFC for that.

This review is far from complete, but I wanted to weigh in early.

You did well. Consider that this is just the beginning of the process :)

[ioggstream]

Since YAML is evolving, it can be valuable for implementers to explain that in the internet you can find documents relying on 1.1 features like https://yaml.org/type/