Documentation enhancement plan

[benjaminhuo]

Docs about the following topics are necessary:

• Separated docs for each OpenFunction version
• Add guide to install sync and async runtime separately using Helm
• Build functions including build functions locally using pack cmd
• Add skywalking tracing guide
• Add go proxy setting guide
• Customize go functions-framework version
• Customize nodejs functions-framework version
• Multi-input topics/bindings examples for async function
• Java Function Samples
• OpenFunction Gateway

see also https://keda.sh/docs/2.3/faq/#using-multiple-triggers-for-the-same-scale-target

[benjaminhuo]

@Patrick-LuoYu Can someone from the documentation team help on the first item?

• Separated docs for each OpenFunction version

OpenFunction docs needs something like https://kubesphere.io/docs/v3.3/