fix(docs): update expiration-date redirect to proper destination

Update the redirect for /platform/features/expiration-date to point to
/cookbooks/essentials/memory-expiration-short-and-long-term instead of
the homepage, matching the link updates in this PR.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/docs.json

@@ -622,7 +622,7 @@
     },
     {
       "source": "/platform/features/expiration-date",
-      "destination": "/"
+      "destination": "/cookbooks/essentials/memory-expiration-short-and-long-term"
     },
     {
       "source": "/platform/features/async-mode-default-change",