Docs: provider invalidation flow so every logout forces a full Discord re-login

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

addCommunityMediaServer.sh

@@ -154,7 +154,8 @@ AUTHENTIK FORWARD-AUTH (gates https://$LIVE/ and https://$BOT/; later the main h
   1. Applications -> Outposts -> edit "authentik Embedded Outpost" -> config: authentik_host: https://$AUTH
   2. Applications -> Create with provider -> Application "Vanguard sites"; Proxy Provider, authorization
      flow implicit-consent, mode "Forward auth (domain level)", authentication URL https://$AUTH,
-     cookie domain ${BASE}   -> then edit the Embedded Outpost -> Applications: add it -> Update
+     cookie domain ${BASE}, Invalidation flow default-provider-invalidation-flow (logout = full re-login)
+     -> then edit the Embedded Outpost -> Applications: add it -> Update
   3. Per-host access is enforced by Caddy from X-Authentik-Groups: .env BOT_REQUIRE_GROUP=bot-users
      (default), LIVE_REQUIRE_GROUP= (empty = any logged-in member). ./configure.py apply regenerates.
   4. Discord roles -> Authentik groups: Directory -> Groups: create bot-users (keep streamers/editors/admins);