Document how to convert configuration from NIC to NGF

[sjberman]

As a user of NGINX Ingress Controller and potential user of NGINX Gateway Fabric
I want a guide that shows me how to convert my configuration expressed in Ingress, VirtualServer, VirtualServerRoute, and annotations to NGINX Gateway Fabric resources with the same configuration
So that I can understand how Gateway API translates the configuration I already have
And so that my path to using Gateway API in my environment is easier.

Acceptance

• Write a new document on how to convert NIC configuration to NGF configuration for:
  • Ingress
  • VirtualServer
  • VirtualServerRoute
  • All annotations supported by NGF

Dev Notes

• This could involve utilizing https://github.com/kubernetes-sigs/ingress2gateway for some of it