fix gateway sample manifest file no apiversion (#16621)

Signed-off-by: xin.li <[email protected]>

Author: my-git9

content/en/docs/ambient/usage/waypoint/index.md

@@ -210,6 +210,7 @@ The keyword `All` may be specified as the value for `allowedRoutes.namespaces.fr
 The following `Gateway` would allow resources in a namespace called "cross-namespace-waypoint-consumer" to use this `egress-gateway`:
 
 {{< text syntax=yaml >}}
+apiVersion: gateway.networking.k8s.io/v1
 kind: Gateway
 metadata:
   name: egress-gateway

content/en/docs/ambient/usage/waypoint/snips.sh

@@ -128,6 +128,7 @@ pod/reviews-v2-5b667bcbf8-spnnh labeled
 ENDSNIP
 
 ! IFS=$'\n' read -r -d '' snip_configure_a_waypoint_for_crossnamespace_use_1 <<\ENDSNIP
+apiVersion: gateway.networking.k8s.io/v1
 kind: Gateway
 metadata:
   name: egress-gateway