chore: wire simplex docs into sidebar + AUTHOR_MAP

- Adds plugins/platforms/simplex docs page to the messaging sidebar
  between LINE and Open WebUI.
- Maps louismichalot@hotmail.com -> Mibayy in scripts/release.py so the
  attribution check on the salvage PR passes.

website/sidebars.ts

@@ -145,6 +145,7 @@ const sidebars: SidebarsConfig = {
         'user-guide/messaging/teams-meetings',
         'user-guide/messaging/msgraph-webhook',
         'user-guide/messaging/line',
+        'user-guide/messaging/simplex',
         'user-guide/messaging/open-webui',
         'user-guide/messaging/webhooks',
       ],