Update entity_relationship_generator.py

entity_relationship_generator.py

@@ -11,6 +11,9 @@ def generate_entity_relationship_diagram(json_input: str, output_format: str) ->
         json_input (str): A JSON string describing the ER diagram structure.
                           It must follow the Expected JSON Format Example below.
 
+        output_format (str): The output format for the generated diagram.
+                            Supported formats: "png" or "svg"
+
     Expected JSON Format Example:
     {
       "entities": [