add a few more docsrs feature hint for when visibility::make is used

follows !706 (merged)

I don't like having a #[rustfmt::skip] but otherwise there is a linebreak in a cfg_attr which is not yet supported by check_doc_features.

So either we want the doc to be (more) right for 1.0 and this will have to do, or we are not in a hurry to get the doc in sync, and the script should be made to parse files in less of a line-based fashion before merging.