Update quickstart to enable using DEV Build

[gyliu513]

What steps did you take and what happened:
[A clear and concise description on how to REPRODUCE the bug.]

The current quickstart guide is using 0.1.0 release at https://github.com/kubernetes-sigs/cluster-api-provider-nested/tree/main/docs#init-control-plane-infrastructure-etc , but for developers, it would be great if there are some steps to customize, like enabling DEV build, turn on/off some feature flag etc.

@christopherhein @charleszheng44 comments? If you are good with this proposal, I can create a PR for this.

What did you expect to happen:

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• cluster-api-provider-nested version:
• Minikube/KIND version:
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):

/kind bug
[One or more /area label. See https://github.com/kubernetes-sigs/cluster-api-provider-nested/labels?q=area for the list of labels]

[charleszheng44]

@gyliu513 Yes, I agree, a DEV build option would be good. But we are using clusterctl now, which will fetch prebuild release image. If developers wanna use a customized image, it usually includes the following steps

1. build the NCP controller image locally
2. use kind load docker-image to load the local-built image to the kind cluster
3. change the clusterctl config to use the local-built image.

I am not sure if this is too complicated for a quick start guide. I think we should write a doc just for developers, like Development Manual. What do you think?

[christopherhein]

Agree, maybe we can make a docs/dev-quickstart.md we used to have that in the docs/README.md if you check thee history on https://github.com/kubernetes-sigs/cluster-api-provider-nested/commits/main/docs/README.md the first couple commits before we brought in clusterctl you should be able to copy the steps from there.

[gyliu513]

Thanks @charleszheng44 @christopherhein , +1 for a new doc, let me create a new one for dev.

/assign