Research/update keepalived example for maxscale

For the purpose of ease of use / HA maxscale, some customers want to use keepalived for two reasons

• not all connectors support multiple ip/address/hostnames (for 2 or more maxscales)
• abstracting maxscale failure/new maxscale ips from being an application configuration change

other considerations:

• document different kind of health checks? vs if just maxscale is running