Eleven host pages (overview, instances, storages, networks, interfaces,
nwfilters, secrets and their item pages) each carried their own copy of
the links to the host's sections, as a breadcrumb: the sections are
siblings, not a path, and on a phone the separators were left at the
start of wrapped lines. The item pages marked no section at all.
computes/host_nav.html is the one nav, labelled "Host sections": pills
that wrap, the page's section marked active, with aria-current="page"
on the section's own page and "true" on an item of it.
