Adding initial EndpointSlice documentation (#16018)

content/en/docs/concepts/services-networking/service.md

@@ -184,6 +184,19 @@ An ExternalName Service is a special case of Service that does not have
 selectors and uses DNS names instead. For more information, see the
 [ExternalName](#externalname) section later in this document.
 
+### Endpoint Slices
+{{< feature-state for_k8s_version="v1.16" state="alpha" >}}
+
+Endpoint Slices are an API resource that can provide a more scalable alternative
+to Endpoints. Although conceptually quite similar to Endpoints, Endpoint Slices
+allow for distributing network endpoints across multiple resources. By default,
+an Endpoint Slice is considered "full" once it reaches 100 endpoints, at which
+point additional Endpoint Slices will be created to store any additional
+endpoints.
+
+Endpoint Slices provide additional attributes and functionality which is
+described in detail in [Endpoint Slices](/docs/concepts/services-networking/endpoint-slices/).
+
 ## Virtual IPs and service proxies
 
 Every node in a Kubernetes cluster runs a `kube-proxy`. `kube-proxy` is
@@ -1148,5 +1161,6 @@ which encompass the current ClusterIP, NodePort, and LoadBalancer modes and more
 
 * Read [Connecting Applications with Services](/docs/concepts/services-networking/connect-applications-service/)
 * Read about [Ingress](/docs/concepts/services-networking/ingress/)
+* Read about [Endpoint Slices](/docs/concepts/services-networking/endpoint-slices/)
 
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