controller

It would be good to add proper building instructions for Windows (installing packages/libs etc.) in BUILDING.md.
Preferably using msys2. It is already used with CI. It works good and allows installing multiple tools and libraries for windows.

We should add a new make dev-env entry in Makefile, to start a dev environment.

It should do something:

• using kind create a new cluster
• Deploy APISIX + etcd
• Build apisix-ingress-controller’s image
• Deploy apisix-ingress-controller

Most of them are already contained in the current Makefile, we need to organize them

It would be good to add a mention about healthEndpoint to documentation as it is super useful when using urlFrom.ingressRef

At least I could not easily find the complete list of supported values. Luckily found a mention in https://github.com/stakater/IngressMonitorController/blob/master/docs/migration-guide.md

It is not the first doc to read as I started using the operator from the start.