[Feedback]: Kibana Fleet APis are missing in 8.x branch

[philippkahr]

THis https://www.elastic.co/guide/en/fleet/8.18/fleet-apis.html
is missing in https://www.elastic.co/docs/api/doc/kibana/v8/

[lcawl]

The APIs are picked up by being present in https://github.com/elastic/kibana/blob/main/.buildkite/scripts/steps/checks/capture_oas_snapshot.sh
It looks like the inclusion of Fleet APIs wasn't backported past V9 when they were added via elastic/kibana#194788
Thus if they're ready for inclusion the capture_oas_snapshot.sh needs to be updated in 8.19 and 8.18 branches.