Expand documentation of annotations used in manifests and KRM functions API (#3995)

* Expand documentation of annotations used in manifests and KRM function wire format.

- Reserve `internal.config.kubernetes.io` for control annotations
- Document `local-config` annotation in a seperate document (It's
  orthogonal to KRM functions).
- There is a internal annotation that uses `config.k8s.io` instead of
  `config.kubernetes.io` used by other annotations. See [1] and [2]. We
  should avoid using two seperate annotation prefixes and audit the
  codebase for any other annotation. Given the `id` control annotation is used
  for comment preservation (no existing function should be modifying
  it), I suggest moving this over to use
  `fn-ctrl.config.kubernets.io/id`.

[1]: 7e8ba62e9f/kyaml/fn/runtime/runtimeutil/runtimeutil.go (L195)
[2]: https://github.com/kubernetes-sigs/kustomize/pull/2465

* Move path/index annotation to use internal prefix

* Clarify MUST NOT vs SHOULD NOT for internal annotations

* Update cmd/config/docs/api-conventions/functions-spec.md

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

* Update cmd/config/docs/api-conventions/functions-spec.md

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

* Update cmd/config/docs/api-conventions/manifest-annotations.md

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

* Remove kusotmization as example

Co-authored-by: Katrina Verey <kn.verey@gmail.com>

cmd/config/docs/api-conventions/manifest-annotations.md

@@ -0,0 +1,11 @@
+# Manifest Annotations
+
+This document lists the annotations that can be declared in resource manifests.
+
+### `config.kubernetes.io/local-config`
+
+A value of `"true"` for this annotation declares that the resource is only consumed by
+client-side tooling and should not be applied to the API server.
+
+A value of `"false"` can be used to declare that a resource should be applied to
+the API server even when it is assumed to be local.