docs: add OBJECT_STORAGE_PUBLIC_ENDPOINT environment variable

Author: inkeep[bot]

contents/docs/self-host/configure/environment-variables.md

@@ -74,6 +74,7 @@ Some variables here are default Django variables. This [Django Docs page](https:
 | `STATSD_PREFIX`                                                                                          | Prefix to be prepended to all stats used by StatsD. Useful for distinguishing environments using the same server.                                                                                                                                   | _Empty_                                                                                                       |
 | `CLEAR_CLICKHOUSE_REMOVED_DATA_SCHEDULE_CRON`                                                            | When data is (asynchronously) deleted from the events table                                                                                                                                                                                         | `0 5 * * SAT`                                                                                                 |
 | `LOG_LEVEL`                                                            | The log level for the plugin server.                                                                                                                                                                                         | `info`                                                                                                 |
+| `OBJECT_STORAGE_PUBLIC_ENDPOINT`                                                                         | Public-facing endpoint used for generating presigned URLs. Required when the internal object storage endpoint differs from the externally accessible URL (common in hobby deployments behind a reverse proxy). | Defaults to `OBJECT_STORAGE_ENDPOINT`                                                                         |
 
 ## Instance settings