[Document] should add guides to teach an addon contributor how to run&debug an addon.

[weicao]

for example, after I modify some YAML files under an addon directory, how could I upgrade the existing addon in a remote K8s cluster.

We should have some guides to use commands like helm template ./deploy/llm/ | kubectl apply -f - or helm upgrade -i neon deploy/neon for developper who're not that familiar with Kubeblocks and helm.