DOC: edit help for 'save-and-restore' tool

Author: dmgav

src/save_and_restore_api/tools/cli.py

@@ -87,7 +87,6 @@ def formatter(prog):
     parser = argparse.ArgumentParser(
         description="save-and-restore: CLI tool for operations on Save-and-Restore nodes.\n"
         f"save-and-restore-api version {version}\n\n"
-        "The tool connects to the save-and-restore service to perform the selected operation. \n"
         "The following operations are currently supported:\n"
         "    LOGIN: check user login credentials.\n"
         "    CONFIG GET: read an existing config node.\n"
@@ -106,8 +105,11 @@ def formatter(prog):
         "    SAVE_AND_RESTORE_API_USER_PASSWORD: user password (use with caution).\n"
         "CLI parameters override the respective environment variables.\n"
         "\n"
-        "The program returns 0 if the operation is successful. Non-zero return codes\n"
-        "indicate errors.\n"
+        "\n"
+        "Exit codes:\n"
+        "    0: operation successful;\n"
+        "    1: error in command line parameters;\n"
+        "    2: operation failed.\n"
         "\n"
         "Examples:\n"
         "\n"