Resolve "external backup on S3"

Closes #26 (closed)

roles/ynh_backup/README.md

@@ -39,7 +39,7 @@ ynh_backup:
 - `ynh_backup.scheduled_[hour|minute|weekday|month]`: modifies the scheduling of the cron task. By default, it will run every day of the year at 3am. For more information about cron time settings, this tool can be useful: <https://crontab.guru/>.
 - `ynh_backup.system`: Disable YunoHost system backup by setting the value to `False`, the default value is `True`.
 - `ynh_backup.apps`: Disable backup of YunoHost applications by setting the value to `False`, the default is `True`.
-- `ynh_backup.number_days_to_keep` : Determines the number of days to keep for the purging system, the default is 2.
+- `ynh_backup.number_days_to_keep`: Determines the number of days to keep for the purging system, the default is 2.
 - ⚠️ Beware, once you enable the local backup feature `ynh_backup.scheduled`, you cannot disable system **and** application backups. If you set `ynh_backup.system` **and** `ynh_backup.apps` to `False`, the role will fail.
 
 ### remote backups with YunoHost BorgBackup