**Related issue:** N/A
## Summary
Fleet's "Host vitals" label type already supports matching on a custom
host vital's exact value (in addition to the existing IdP-based
criteria), but this wasn't documented anywhere outside the custom host
vitals guide (see companion PR #50660). Adds that coverage across the
remaining references:
- `articles/managing-labels-in-fleet.md`: the "Host vitals" label type
bullet only listed the two IdP criteria; now also mentions custom host
vitals, and notes the type is exact-match only.
- `docs/Configuration/yaml-files.md`:
- Adds a `custom_host_vital` example to the labels GitOps reference,
alongside the existing IdP example.
- Adds a new `## custom_host_vitals` section documenting the top-level
GitOps key used to define vitals in the first place (referenced by the
labels criteria above), which had no reference-doc coverage at all.
Calls out that, unlike `labels`, omitting the key entirely deletes every
existing custom host vital rather than leaving them intact.
- `docs/REST API/rest-api.md`:
- The `criteria` parameter table was missing `custom_host_vital` as a
valid `vital` value and missing `custom_host_vital_id` entirely — added
both.
- None of the 6 registered custom host vitals endpoints (list, create,
update, delete, set a host's value, and the spec/replace-all endpoint
GitOps uses) had reference entries at all. Adds a full "Custom host
vitals" section following the existing "Custom variables" section's
format, including the same destructive replace-all behavior called out
in the YAML reference above.
# Checklist for submitter
- [ ] QA'd all new/changed functionality manually
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Co-authored-by: Rachael Shaw <r@rachael.wtf>
