Documented additional AWS Service annotations (#4864)

docs/concepts/services-networking/service.md

@@ -512,6 +512,37 @@ ELB at the other end of its connection) when forwarding requests.
 TCP and SSL will select layer 4 proxying: the ELB will forward traffic without
 modifying the headers.
 
+In a mixed-use environment where some ports are secured and others are left unencrypted,
+the following annotations may be used:
+
+```yaml
+    metadata:
+      name: my-service
+      annotations:
+        service.beta.kubernetes.io/aws-load-balancer-backend-protocol: http
+        service.beta.kubernetes.io/aws-load-balancer-ssl-ports: "443,8443"
+```
+
+In the above example, if the service contained three ports, `80`, `443`, and
+`8443`, then `443` and `8443` would use the SSL certificate, but `80` would just
+be proxied HTTP.
+
+#### PROXY protocol support on AWS
+
+To enable [PROXY protocol](https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt)
+support for clusters running on AWS, you can use the following service
+annotation:
+
+```yaml
+    metadata:
+      name: my-service
+      annotations:
+        service.beta.kubernetes.io/aws-load-balancer-proxy-protocol: "*"
+```
+
+Since version 1.3.0 the use of this annotation applies to all ports proxied by the ELB
+and cannot be configured otherwise.
+
 ### External IPs
 
 If there are external IPs that route to one or more cluster nodes, Kubernetes services can be exposed on those