Merge pull request 'Add documentation for backups/restores' (#365) from docs/backup into master

Reviewed-on: #365

doc/backups.md

@@ -0,0 +1,15 @@
+Backup
+======
+
+## Backup gem
+
+Backups are stored on AWS S3, in the `kosmos-dev-backups` bucket.
+
+The S3 credentials as well as the backup password are stored in the
+`credentials` data bag under the `backup` item.
+
+### Restore
+
+To decrypt a backup archive, use the following command:
+
+    openssl aes-256-cbc -d -base64 -in my_backup.tar.enc -out my_backup.tar