docs: add missing namespace field to the scale request

[LucasRoesler]

The ScaleFunction request supports specifying the function namespace. This is now included in the API spec.

Motivation and Context

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• My issue has received approval from the maintainers or lead with the design/approved label

This issue was discussed during the last Community call

How Has This Been Tested?

NA

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s
• I have added tests to cover my changes.
• All new and existing tests passed.

[alexellis]

LGTM

This should also be added to the delete operation in the same way if it's not already.