switched to key-based auth for SSH, added docs

compose.sftp.yml

@@ -8,11 +8,8 @@ services:
       - PUID=1000
       - PGID=1000
       - TZ=Etc/UTC
-      - PASSWORD_ACCESS=true
-      - USER_PASSWORD_FILE=/run/secrets/ssh_password
       - USER_NAME=sftp
-    secrets:
-      - ssh_password
+      - PUBLIC_KEY
     volumes:
       - content:/content:rw
     ports:
@@ -36,11 +33,6 @@ services:
       - content:/content:rw
     entrypoint: [ "bash", "-c", "sleep 10 && chown -R 1000:1000 /content"]
 
-secrets:
-  ssh_password:
-    external: true
-    name: ${STACK_NAME}_ssh_password_${SECRET_SSH_PASSWORD_VERSION}
-
 volumes:
   content: