Add config examples for constructing clients

All the current examples rely on config.fromKubeconfig(). Add examples that manually specify some of the config options.

1. create a new example in examples/. The goal is to illustrate how to use basic auth and provide an end-to-end working example. With that in mind, the example should construct a new client instance using basic auth, and make an API call (e.g., get Pods or Deployments) to illustrate functionality.
2. Update README.md the More examples section to include the new example.