Update 1_main_climada.ipynb

I revised the documentation where the terms "vulnerability function" or "damage function" were used, aiming to standardize the communication of CLIMADA's terminology.

doc/tutorial/1_main_climada.ipynb

@@ -482,7 +482,7 @@
     "\n",
     "As with Hazard objects, Entities can be read from files or created through code. The Excel template can be found in `climada_python/climada/data/system/entity_template.xlsx`.\n",
     "\n",
-    "In this tutorial we will create an Exposure object using the LitPop economic exposure module, and load a pre-defined wind damage function."
+    "In this tutorial we will create an Exposure object using the LitPop economic exposure module, and load a pre-defined impact function for asset damages due to storm."
    ]
   },
   {