add description for __meta_kubernetes_endpoints_label_* and __meta_kubernetes_endpoints_labelpresent_* (#10911)
add description for __meta_kubernetes_endpoints_label_* and __meta_kubernetes_endpoints_labelpresent_* (#10911)

* add description for __meta_kubernetes_endpoints_label_* and __meta_kubernetes_endpoints_labelpresent_*

Signed-off-by: renzheng.wang <9eae899f7ca66e2a6eb018426e23761c215cadc6@gmail.com>
prometheus/prometheus,prometheus/prometheus,prometheus/prometheus,prometheus/prometheus,prometheus/prometheus