Rollup merge of #95684 - GuillaumeGomez:fix-item-info-overflow, r=notriddle

Rollup merge of #95684 - GuillaumeGomez:fix-item-info-overflow, r=notriddle

rustdoc: Fix item info display overflow

I came across this issue when reading local `Iterator` docs (reproduced in this screenshot):

![Screenshot from 2022-04-05 17-45-13](https://user-images.githubusercontent.com/3050060/161798150-769ee838-4768-4df8-9d34-b02eb8104eed.png)

The problem comes from the fact that `span` isn't `display: block` by default. Since `item-info` was already present on `<div>` in other places, I moved the last one to `div` as well.

r? `@notriddle`