Scaladoc ARIA landmarks missing in generated HTML documentation

The goal is to make Scaladoc‑generated HTML documentation more accessible by inserting ARIA landmark roles (e.g., role="navigation", role="main", role="complementary") into the page structure so that screen‑reader users can quickly jump to relevant sections.

Uncertainty remains about which elements should receive these roles, whether the addition should be enabled by default or guarded by a Scaladoc flag, and how the change interacts with Scala 2.13.x versus Scala 3.x backends and community plugins such as sbt‑site or mdoc that may already inject markup.

• Which HTML elements (e.g., , , , ) should be assigned ARIA roles to represent navigation, main content, and complementary information?
• Should the landmark injection be the default behavior of Scaladoc or controlled via a command‑line flag or sbt setting?
• How can we ensure that the added landmarks do not conflict with markup generated by existing Scaladoc plugins or alternative documentation backends?