typing slots

issue is open on the repo: https://github.com/vuejs/docs/issues/2371

PR is https://github.com/vuejs/core/pull/7982

doc is missing from here https://vuejs.org/api/utility-types.html
doc is missing from https://vuejs.org/guide/typescript/options-api.html

is documented here: https://vuejs.org/api/options-rendering.html#slots