Add more information to README

README.md

@@ -1,3 +1,29 @@
 # Postgresql backuper
 
 A small program for creating postgresql backups at certain intervals.
+
+
+## Configuration
+
+| Env variable    | Description                                                                           | Default in docker |
+| ---             | ---                                                                                   | ---               |
+| BACKUPS_DIR     |                                                                                       | /backups          |
+| PGDUMP_BINARY   |                                                                                       | pg_dumpall        |
+| CUSTOM_ARGS     | Arguments passed to PGDUMP_BINARY. Don't use `-f`.                                    |                   |
+| BACKUP_INTERVAL | Time between backups.                                                                 | 24h               |
+| RETENTION       | Backups older than the RETENTION period will be deleted.                              | 168h              |
+
+The duration must be in a format understood by the golang's `time` package.
+
+
+## Docker-compose example
+
+```yml
+services:
+  backuper:
+    image: git.comfycamp.space/lumin/postgresql-backuper
+    environment:
+      CUSTOM_ARGS: "-U postgres -h postgresql --no-password"
+    volumes:
+      - postgresql-backups:/backups
+```