add placeholder command for later

examples/example_cell/run_example_cell.sh

@@ -3,4 +3,4 @@ t='data/taxonomy_mapping.csv'
 e='data/exposure.csv'
 g='data/ground_motion_values.csv'
 m='data/intensity_measure_map.csv'
-losscalculator -f $f -m $m -g $g -e $e -t $t --overwrite
+losscalculator damage -f $f -m $m -g $g -e $e -t $t --overwrite

losscalculator/damage_calculator.py

@@ -189,6 +189,12 @@ def main():
         + "exceeding a set of damage states, given an intensity measure level."
     )
 
+    parser.add_argument(
+        "command",
+        type=str,
+        help="'damage' to run a damage assessment",
+        default="damage",
+    )
     parser.add_argument(
         "-i",
         "--interpolation-method",