Restore PostHog analytics on docs and preview (#3233)

preview/vercel.json

@@ -5,6 +5,8 @@
       "status": 308,
       "headers": { "Location": "/marketing.html" }
     },
+    { "src": "/eat/static/(.*)", "dest": "https://eu-assets.i.posthog.com/static/$1" },
+    { "src": "/eat/(.*)", "dest": "https://eu.i.posthog.com/$1" },
     { "handle": "filesystem" },
     {
       "src": "/(.*)",