Documentation: clarify hardware-requirements

[nbykov0]

The part about additional IPs or a load-balancer is not completely clear to me.
I'll clarify that and take action.

[nbykov0]

Also , should "highly availabe application notes" be merged to Production part?

[NickVolynkin]

@nbykov0 we have recently updated this part of documentation, see #166 and https://cozystack.io/docs/guides/faq/#what-if-my-cloud-provider-does-not-support-metallb