getting-started: cleanup "code generation" section
getting-started: cleanup "code generation" section

With this change, the "code generation" section is slightly renamed. I add an explanation about what *is* "generated code" and remove "noisy" note about when not needing to care about it.
davidvossel/kubevirt,kubevirt/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,davidvossel/kubevirt,davidvossel/kubevirt,kubevirt/kubevirt,davidvossel/kubevirt,stu-gott/kubevirt,kubevirt/kubevirt,stu-gott/kubevirt,stu-gott/kubevirt