update docs

Author: mmiller-sh

docs/deploy/configurations.md

@@ -117,6 +117,7 @@ Currently, you can set only 1 namespace to watch in this flag. See [this Kuberne
 | kube-ca-pem-filepath                                                               | string                          |                                            | The file path to the CA to validate webhook callers, when unspecified all webhook callers are permitted.                                                                      |
 | alb-gateway-max-concurrent-reconciles                                           | int                       | 3                                          | Maximum number of concurrently running reconcile loops for ALB gateways, if enabled                                                                                           |
 | nlb-gateway-max-concurrent-reconciles                                           | int                       | 3                                          | Maximum number of concurrently running reconcile loops for NLB gateways, if enabled                                                                                           |
+| max-targets-per-instance                                                        | int                       | 0                                          | Maximum number of targets that will be added to a given ELB instance. The default value of zero will leave the number of targets unlimited                                    |
 
 ### disable-ingress-class-annotation
 `--disable-ingress-class-annotation` controls whether to disable new usage of the `kubernetes.io/ingress.class` annotation.