modify Catalog_example.py doc_string

Catalog/Catalog_example.py

@@ -40,6 +40,8 @@ class Catalog_example(CatalogBase):
         ----------
         config : dict
             configuration dictionary which is parsed from the input YAML file
+        chip: ObservationSim.Instrument.Chip
+            a ObservationSim.Instrument.Chip object, can be used to identify the band etc.
         **kwargs : dict
             other needed input parameters (in key-value pairs), please modify corresponding
             initialization call in "ObservationSim.py" as you need.