docs: phoneHomeEnabled flag lacks explanation of what it injects and how it works #2790

How would you describe the priority of this documentation request
High

Please provide a link or source to the relevant docs

• https://github.com/NVIDIA/infra-controller/blob/main/docs/configuration/tenant_management.md
• https://github.com/NVIDIA/infra-controller/blob/main/docs/manuals/nico-admin-cli/commands/operating-system/operating-system-create.md
• https://github.com/NVIDIA/infra-controller/blob/main/docs/manuals/nico-admin-cli/commands/operating-system/operating-system-update.md

Describe the problems in the documentation
The phoneHomeEnabled flag is documented as a one-liner ("Enable phone-home on first boot") across all three files above. Users who encounter this flag have no way to understand what it actually does without reading source code.

This came up from an ISV trying to delay instance's Ready status until cloud-init finishes applying SSH keys and passwords. The cloud-init behavior is not documented anywhere in public docs.

Specific gaps:

• No explanation of what happens mechanically when the flag is set
• No documentation of what NICo injects into user-data when the flag is enabled
• No guidance on what users should and should not do when using this feature

Code of Conduct

• I agree to follow NVIDIA Infra Controller's Code of Conduct
• I have searched the open documentation issues and have found no duplicates for this documentation issue