Rollup merge of #102744 - notriddle:notriddle/content-item-list, r=GuillaumeGomez

rustdoc: remove unused CSS `.content .item-list`

When these rules were added in 4fd061c426902b0904c65e64a3780b21f9ab3afb (yeah, that's the very first commit of rustdoc_ng), `.item-list` was a `<ul>`, and this would override the default style for that tag.

In c1b1d6804bfce1aee3a95b3cbff3eaeb15bad9a4, it was changed to use a `<div>` tag, so these rules are both no-ops.

diff --cc src/librustdoc/html/static/css/rustdoc.css
Simple merge