docs: document release and tag process

[simitt]

This repo is generally supposed to be stack version independend, but some changes need to be pulled into minor or patch fixes of the stack. New features and bug fixes need to be released in minor and patch versions that can be matched with stack versions. We need to document this.

[leewoobin789]

will there be any frequent release(s) instead of using each commit as package? and the dependencies such as go.opentelemetry.io/collector are quite outdated.

[axw]

@leewoobin789 nothing really decided, but I don't think we'll be creating frequent tagged releases in the near future.