docs: fix yaml for new 'type' in custom metrics

[gadisn]

What this PR does / why we need it:
Fix a docs typo introduced with this PR: #1777

The new 'type' field should be under 'each', see:

https://github.com/kubernetes/kube-state-metrics/blob/master/pkg/customresourcestate/registry_factory.go#L65
https://github.com/kubernetes/kube-state-metrics/blob/master/pkg/customresourcestate/registry_factory.go#L136

How does this change affect the cardinality of KSM: (increases, decreases or does not change cardinality)
None

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #
None

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