Update helm chart README with pluginsCustomConfig flag

Author: rahulgurnani

config/charts/inferencepool/README.md

@@ -124,6 +124,7 @@ The following table list the configurable parameters of the chart.
 | `inferenceExtension.extraServicePorts`      | List of additional service ports to expose. Defaults to `[]`.                                                          |
 | `inferenceExtension.flags`                  | List of flags which are passed through to endpoint picker. Example flags, enable-pprof, grpc-port etc. Refer [runner.go](https://github.com/kubernetes-sigs/gateway-api-inference-extension/blob/main/cmd/epp/runner/runner.go) for complete list.                                                            |
 | `inferenceExtension.flags.has-enable-leader-election` | Enable leader election for high availability. When enabled, only one EPP pod (the leader) will be ready to serve traffic.       |
+| `inferenceExtension.pluginsCustomConfig`    | Custom config that is passed to EPP as inline yaml.      |
 | `provider.name`                             | Name of the Inference Gateway implementation being used. Possible values: `gke`. Defaults to `none`.                   |
 
 ## Notes