Add Kube credentials in the inventory source picker

[tvo318]

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• I agree to follow this project's code of conduct.
• I have checked the current issues for duplicates.
• I understand that AWX is open source software provided for free and that I might not receive a timely response.

Feature type

Enhancement to Existing Feature

Feature Summary

Doc update for new inventory source for "Kube" creds.

Select the relevant components

• UI
• API
• Docs
• Collection
• CLI
• Other

Steps to reproduce

1. Go to: https://ansible.readthedocs.io/projects/awx/en/latest/userguide/inventories.html#inventory-sources
2. Add "Kube" to list of available inventory sources from the Inventories resource

Current results

Missing "Kube" inventory source

Sugested feature result

This would accompany PR #15223

Additional information

No response