- tests/test_breadcrumbs.py: the Prometheus target list is its section's
own top page, like SNMP's, so it carries no trail.
- The integration test's exposition has label braces, which str.format read
as fields: the fake scrape raised, the target was recorded down and no
series landed. It substitutes the counter with replace() now.
- docs/plugins/prometheus.md: adding a target, filtering, how series are
named and stored, alerting, and the Fabled Archives recipe.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>