[core-aam PR 117] Generic Role Section

[pkra]

Moved from https://github.com/w3c/core-aam/pull/117/

Original description:

Adds a new section: 4.4.3 Role Mapping for Generic Host Language Elements.

Submitted early for feedback before continuing.

This may eventually Resolve #112.

Preview: https://raw.githack.com/w3c/aria/monorepo_history--core-aam-PR117/core-aam/index.html#mapping_generic_role