[DOCS] Add known issue to 8.14 release notes

[lcawl]

Summary

Relates to #186969

This PR adds a known issue in the Kibana release notes.

[obltmachine]

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Just comment with:

• /oblt-deploy : Deploy a Kibana instance using the Observability test environments.
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[elasticmachine]

Pinging @elastic/obs-ux-management-team (Team:obs-ux-management)

[pmuellr]

LGTM

[kibanamachine]

💚 All backports created successfully

Status	Branch	Result
✅	8.14
✅	8.15

Note: Successful backport PRs will be merged automatically after passing CI.

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