"Warnings" in docs show blank lines with numbers if line numbers in examples are turned on

[paul-hansen]

Bug Report

Version

main and latest (e.g. tracing/0.1.41) on docs.rs

Crates

tracing
tracing-subscriber
tracing-core

Description

Turning on "Show line numbers on code examples" in the documentation shows line numbers above the warnings in some of the tracing crates. This seems to be because tracing crates use the example-wrap class for their warnings.

Show example image of how to turn on line numbers

Example

From https://docs.rs/tracing/0.1.41/tracing/index.html

Proposed solution

It looks like rustdoc has a documented way to format a warning block, maybe that should be used? I'd be happy to make a PR if desired.
https://doc.rust-lang.org/rustdoc/how-to-write-documentation.html#adding-a-warning-block