Remove misleading documentation about config generation

[VannTen]

/kind cleanup

Follow-up to #3146, cleaning examples as well.

(Note that this files appeart pretty high in search results when looking for "kustomize configmap generation", so I guess I'm not the first one to be confused ^)

[VannTen]

/kind documentation

[stormqueen1990]

Hi there, @VannTen!

Could you please rebase your PR? It appears we had a linting issue on master that is causing your PR to fail the lint check.

[VannTen]

done :+1:

[koba1t]

/assign @stormqueen1990

[koba1t]

Thanks @VannTen /approve

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