[DOCS 1496] Update kube-apiserver-metrics readme with cluster agent note (#8780)
[DOCS 1496] Update kube-apiserver-metrics readme with cluster agent note (#8780)

Co-authored-by: Kaylyn <f0618a96b1184250d2a1d10914215211f1dbdbee@datadoghq.com>
DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core,DataDog/integrations-core