Add missing supports for kubernetes client stable and gold

[mbohlool]

according to new kubernetes client guidelines python client is beta support and has silver capabilities. We are almost there to have gold capabilities and stable support. missing parts are:

Gold:

• [ ] Support attach, port-forward calls
• [ ] Proto encoding
• [ ] Generated examples #252 #219

Stable:

• [ ] N documented users of the library
• [ ] Support level documented per-platform
• [ ] Deprecation policy (backwards compatibility guarantees documented)
• [ ] Release process well documented