add copycomp Makefile targets for component docs

[Caesarsage]

What

Three new make targets that copy gen-compdocs/build/ output into the corresponding hand-curated destinations under k/website:

Target	Source	Destination
copycomp-core	kube-apiserver.md, kube-controller-manager.md, kube-scheduler.md, kube-proxy.md	content/en/docs/reference/command-line-tools-reference/
copycomp-kubeadm	kubeadm.md + every kubeadm_*/ subdir	content/en/docs/reference/setup-tools/kubeadm/generated/
copycomp-kubectl	kubectl.md + every kubectl_*/ subdir	content/en/docs/reference/kubectl/generated/

Plus a copycomp umbrella that runs all three.

Why

Mirrors the per-component handoff pattern @tengqm described — each component's regenerated docs go into its specific hand-curated tree (which contains curated _index.md, README.md, and unrelated subdirs like feature-gates/), so we overlay rather than rm -rf.

Verification

• make -n copycomp-core clean syntax
• End-to-end run against a real k/website tree: 4 kube-* files copied to command-line-tools-reference/, kubeadm tree copied with 11 subdirs, kubectl tree copied with 45 subdirs. No errors.

[tengqm]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Caesarsage, tengqm

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