rustdoc: remove outdated CSS `.sub-variant > div > .item-info`

This CSS still matches sometimes, as you can see in
<https://doc.rust-lang.org/1.63.0/std/collections/enum.TryReserveErrorKind.html#variant.AllocError.fields>,
but since nothing else is setting `margin-top`, putting it back to `initial`
does nothing.

This selector was added in 2fd378b82b14f2746462018e8510e15a079818a0 (but it
was called `.stability` instead of `.item-info` at the time), probably as an
override for the selector immediately above it that sets a negative margin.
That negative margin was removed in 593d6d1cb15c55c88319470dabb40126c7b7f1e2.

0 files changed, 0 insertions, 0 deletions