update readme and add disclaimer

migration/README.md

@@ -1,9 +1,15 @@
 # Migrate From Existing Server
 
+> [!WARNING]
+> Use this script at your own risk, I am not responsible for dataloss!
+>
+> Please make sure you always have a backup!
+
 1. Find a directory which is named by game server name and contains all saved game data,
    usually it will at `~/Steam/steamapps/common/PalServer/Pal/Saved/SaveGames/0/`
-3. Make sure `migration/migrate.sh`, saved game data directory and mounted volume (e.g. `palworld/`) are in the same directory. Like this:
-
+2. Make sure `migration/migrate.sh`, saved game data directory and mounted volume
+   (e.g. `palworld/`) are in the same directory. Like this:
+
     ```shell
     ubuntu@VM-4-5-ubuntu:~/test-pal-migrate$ ll
     total 24
@@ -15,7 +21,7 @@
     drwxrwxr-x  7 ubuntu ubuntu 4096 Jan 26 03:31 palworld/
     ```
 
-5. Run `migrate.sh` like this
+3. Run `migrate.sh` like this
 
     ```shell
     ./migrate.sh {CONTAINER_NAME} {SERVER_NAME}