Document different kinds of selector-combinators

[kitten]

I must admit I can't with certainty tell what the ones except the first one are. I could probably figure this out by thinking about all the different combinators a bit more, but it made me realise that the spec needs a section on what they are :wink:

const SPACE_COMBINATOR = 5
const DOUBLED_CHILD_COMBINATOR = 6
const CHILD_COMBINATOR = 7
const NEXT_SIBLING_COMBINATOR = 8
const SUBSEQUENT_SIBLING_COMBINATOR = 9

cc @kof

[kof]

terminology is taken from the spec

[kof]

https://drafts.csswg.org/selectors/#combinators

[kitten]

Ah! Perfect thanks 😅