docs: fix confusing loopback IPs in environment setup

[jkomg]

Currently, the "Setup Environment" code block defines MACHINE_0_ADDRESS and MACHINE_1_ADDRESS using loopback addresses (127.0.0.1). This is causing confusion for developers who assume these are valid defaults or that the step applies to a local deployment. Furthermore, these variables are not used in the Secret generation block below them.

This PR updates the documentation to use explicit, non-routable documentation IP addresses (192.0.2.x) and adds a comment explicitly telling developers to replace them.

Changes to the Documentation Page
Change this:

# Setup Environment
KEY_PATH=~/.ssh/id_ed25519
PRIVATE_SSH_KEY_B64=$(cat $KEY_PATH | base64 -w 0)
SECRET_NAME=remote-ssh-key
KCM_SYSTEM_NS=kcm-system
CREDENTIAL_NAME=remote-cred
RESOURCE_TEMPLATE_NAME=remote-ssh-key-resource-template
CLUSTER_DEPLOYMENT_NAME=my-remote-clusterdeployment1
MACHINE_0_ADDRESS=127.0.0.1
MACHINE_1_ADDRESS=127.0.0.2

# Setup Environment
KEY_PATH=~/.ssh/id_ed25519
PRIVATE_SSH_KEY_B64=$(cat $KEY_PATH | base64 -w 0)
SECRET_NAME=remote-ssh-key
KCM_SYSTEM_NS=kcm-system
CREDENTIAL_NAME=remote-cred
RESOURCE_TEMPLATE_NAME=remote-ssh-key-resource-template
CLUSTER_DEPLOYMENT_NAME=my-remote-clusterdeployment1

# REPLACE THESE: Target IP addresses of your actual remote nodes
MACHINE_0_ADDRESS=192.0.2.10
MACHINE_1_ADDRESS=192.0.2.11

Why this fix works better:

The Comment Flag: Adding # REPLACE THESE explicitly tells a developer scanning the code that action is required on their part.

RFC 5737 Documentation IPs: Using 192.0.2.X addresses is the industry standard for documentation. They are explicitly reserved for examples and are completely unroutable, meaning if a developer accidentally copy-pastes them, the script will instantly fail cleanly with a "network unreachable" or "timeout" error, rather than behaving strangely on localhost.