Merge pull request #46955 from seans3/kep-4006-portforward-docs

[KEP-4006] - Docs for PortForward over WebSockets Feature Gates (Beta)

Author: k8s-ci-robot

content/en/docs/reference/command-line-tools-reference/feature-gates/port-forward-websockets.md

@@ -9,6 +9,10 @@ stages:
   - stage: alpha
     defaultValue: false
     fromVersion: "1.30"
+    toVersion: "1.30"
+  - stage: beta
+    defaultValue: true
+    fromVersion: "1.31"
 ---
 Allow WebSocket streaming of the
 portforward sub-protocol (`port-forward`) from clients requesting