Update k3d cluster create example

[brooke-hamilton]

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Description

This PR updates the recommended command to use when creating a k3d cluster by adding a parameter to the k3d cluster create command to disable the default load balancer. The default load balancer was conflicting with the load balancer deployed by Radius. See the issue reference linked below for details.

Note: traefik@server:0 was changed to traefik@server:* to indicate that all instances should be affected, not just the one at index zero.

Issue reference

Fixes: radius-project/radius#7637

[Reshrahim]

LGTM. Thanks for the detailed explanation of the args.