Ajout detail usage commandes import/export acl

vm/import_acl.py

@@ -29,6 +29,14 @@ def import_acls(input_file):
 def main():
     if len(sys.argv) != 2:
         print(f"Usage: {sys.argv[0]} <input_file>")
+        print("""
+Arguments:
+    input_file  - File containing ACLs to import
+
+Input file format:
+    <acl-path> <user>@<realm> <role>
+    <acl-path> <user>@<realm> <role>
+    ...""")
         sys.exit(1)
 
     input_file = sys.argv[1]