Style guide: add descriptions

[martinbonnin]

Thanks for the style guide ❤️

I was wondering if there were any recommendations how to write descriptions?

The spec says it's markdown but is there anything on top of that to link to other fields or indicate parameters and other things?
Like @link and @param in Javadoc?

[benjie]

As far as I know, no such convention currently exists. However we do have Schema Coordinates now, so using these for this purpose seems wise. I wonder if `Type` and `Type.fieldName` should auto-link to the relevant places in the API?

[martinbonnin]

That'd be cool!