docs: add ssh backup example

docs/how-tos/backup-to-ftp.md

@@ -0,0 +1,44 @@
+---
+title: Backup to FTP remote server
+layout: default
+parent: How Tos
+nav_order: 4
+---
+# Backup to FTP remote server
+
+
+As described for s3 backup section, to change the storage of your backup and use FTP Remote server as storage. You need to add `--storage ftp`.
+You need to add the full remote path by adding `--path /home/jkaninda/backups` flag or using `REMOTE_PATH` environment variable.
+
+{: .note }
+These environment variables are required for SSH backup `FTP_HOST_NAME`, `FTP_USER`, `REMOTE_PATH`, `FTP_PORT` or `FTP_PASSWORD`.
+
+```yml
+services:
+  pg-bkup:
+    # In production, it is advised to lock your image tag to a proper
+    # release version instead of using `latest`.
+    # Check https://github.com/jkaninda/pg-bkup/releases
+    # for a list of available releases.
+    image: jkaninda/pg-bkup
+    container_name: pg-bkup
+    command: backup --storage ftp -d database
+    environment:
+      - DB_PORT=5432
+      - DB_HOST=postgres
+      - DB_NAME=database
+      - DB_USERNAME=username
+      - DB_PASSWORD=password
+      ## FTP config
+      - FTP_HOST_NAME="hostname"
+      - FTP_PORT=21
+      - FTP_USER=user
+      - FTP_PASSWORD=password
+      - REMOTE_PATH=/home/jkaninda/backups
+
+    # pg-bkup container must be connected to the same network with your database
+    networks:
+      - web
+networks:
+  web:
+```