Side menu on imported `docs/` is buggy

[ChrisBAshton]

See https://docs.publishing.service.gov.uk/repos/search-api/public-api/faceted-search.html:

Issues:

• Top level docs/*.md files should appear first. Instead, the arch/ folder appears first.
• Top level docs/*.md files appear to be bundled into the arch/ folder
• The Faceted search doc under docs/public-api appears twice