Create a policy.

Creates a policy from the request body under the given name. A name the owner already uses is refused with 409; replace an existing policy with PUT /api/policies/{policyName}. The policy is validated before it is stored. To set the description and notes in the same write, pass details=true and send {"policy": <the policy>, "description": "...", "notes": "..."}; description and notes are optional, a field left out or null is left as it is, and an empty value clears it. Without details=true the body is the policy itself. Admins may create a policy in another user's account by passing that user's username as owner. Requires the policies:write scope.