Broken styling for GitHub Markdown alerts in Specification pages

[vitorvasc]

Description

GitHub Markdown alerts were previously enabled in #8445. However, following the latest Specification release, it was reported via the #otel-specification Slack channel that these alerts are no longer rendering correctly.

This issue also relates to #5557.

Examples

The Supplementary Guidelines section in Docs / Specs / OTel 1.52.0 / Context / Environment Variables as Context Propagation Carriers contains an alert migrated to the new syntax in https://github.com/open-telemetry/opentelemetry-specification/pull/4784. While the alert renders correctly when viewed directly in the GitHub repository, the styling is missing when viewed on the opentelemetry.io website.

URL: https://github.com/thompson-tomo/opentelemetry-specification/blob/e874e2addba7c80de2e416e5aa5fedb2b26bb077/specification/context/env-carriers.md#supplementary-guidelines

URL: https://opentelemetry.io/docs/specs/otel/context/env-carriers/#supplementary-guidelines