docs: add redirects for /whl and /whl/:path* to external documentatio… (#23395)

docs_new/docs.json

@@ -16,6 +16,16 @@
       "source": "/cookbook",
       "destination": "/cookbook/intro"
     },
+    {
+      "source": "/whl",
+      "destination": "https://sgl-project.github.io/whl/",
+      "permanent": false
+    },
+    {
+      "source": "/whl/:path*",
+      "destination": "https://sgl-project.github.io/whl/:path*",
+      "permanent": false
+    },
     {
       "source": "/index.html",
       "destination": "/"