Refine metadata used by Google Search for breadcrumbs in results

These results should show a CI level at the top, e.g.:

docs.gitlab.com > CI > variables > predefined_variables

Not sure if the last term should be left off, or refined to show as "Predefined Variables" or as the page title.

Google docs on breadcrumbs: https://developers.google.com/search/docs/appearance/structured-data/breadcrumb