docs: Add NGF installation steps to README (#11)

Author: sjberman

Diff for: nginx-gateway-fabric/appworld/README.md

@@ -1,3 +1,15 @@
 # NGINX Gateway Fabric Demo
 
 This demo contains the files used in the NGINX Gateway Fabric AppWorld demo.
+
+To install the Gateway API CRDs:
+
+```shell
+kubectl kustomize "https://github.com/nginx/nginx-gateway-fabric/config/crd/gateway-api/standard?ref=v1.6.1" | kubectl apply -f -
+```
+
+To install NGINX Gateway Fabric:
+
+```shell
+helm install ngf oci://ghcr.io/nginx/charts/nginx-gateway-fabric --create-namespace -n nginx-gateway
+```