Publish v2 /health and /ready readiness-gate API docs on next OSS v2 release

[jstirnaman]

Tracking issue for releasing the updated /health and /ready API reference docs once the next InfluxDB OSS v2.x ships the readiness-gate behavior.

Context

influxdata/influxdb#27370 added readiness gates and richer /health + /ready responses to influxd. It is merged to main-2.x but unreleased (docs currently track v2.9.1).

• Spec update: feat(v2): document /ready readiness gates in OpenAPI spec #7286 — adds the /ready 503 response and extends the Ready schema (starting status + failing-only checks). Labeled release:pending.
• Source-repo operator doc: influxdata/influxdb#27477 — reviewed for style; kept as an in-repo engineering reference (niche audience), not ported to the docs site.

Tasks

• Confirm the InfluxDB OSS v2.x version that ships feat: make /health and /ready available early influxdb#27370, and rename this milestone to that version.
• Land the spec change upstream in influxdata/openapi, or it will be overwritten on the next getswagger.sh regen.
• When that v2 version releases: flip feat(v2): document /ready readiness gates in OpenAPI spec #7286 release:pending → release:ready, then review and merge.