Update self-host/customize-deployment/configure-a-slack-app-for-lightdash.mdx (#344)

Co-authored-by: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>

Author: mintlify[bot]

self-host/customize-deployment/configure-a-slack-app-for-lightdash.mdx

@@ -39,6 +39,7 @@ features:
 oauth_config:
   redirect_urls:
     - https://your-lightdash-deployment-url.com/api/v1/slack/oauth_redirect
+    - https://your-lightdash-deployment-url.com/api/v1/auth/slack/callback
   scopes:
     bot:
       - app_mentions:read