Add documentation for bootstrapping RDMA

[AlexCheema]

Currently the macOS app runs some swift code / a bash script on start to bootstrap RDMA but this is not documented when running from source. There are known issues e.g. having Thunderbolt Bridge enabled causing packet storms.

[Evanev7]

We should remove the bulk of this logic after #928 lands

[pbrass]

@AlexCheema should I disable Thunderbolt Bridge on every computer in the cluster? Definitely saw those packet storms when I plugged everything in… I think it is still enabled on at least one computer and the cluster is unusably fragile… Is there a network setup best practices guide anywhere?

[Evanev7]

generally yes - disable bridge on all devices if you have 3 or more.