Single-line yields render as parameter names in docs

[paddyroddy]

Fantastic effort, particularly with the many changes in specs! There is a remaining issue with single-line yields but it's so minuscule that I want to tackle it separately. Towards a new release!

Originally posted by @ntessore in #381 (review)

[ntessore]

Single-line returns without variable names appear to be special-cased, so this probably requires to give all yields a name: line. Low priority.