add drop frame documentation

Author: cezannec

intro-neural-networks/student-admissions/StudentAdmissions.ipynb

@@ -117,7 +117,9 @@
     "This looks more promising, as it seems that the lower the rank, the higher the acceptance rate. Let's use the rank as one of our inputs. In order to do this, we should one-hot encode it.\n",
     "\n",
     "## TODO: One-hot encoding the rank\n",
-    "Use the `get_dummies` function in pandas in order to one-hot encode the data."
+    "Use the `get_dummies` function in pandas in order to one-hot encode the data.\n",
+    "\n",
+    "Hint: To drop a column, it's suggested that you use `one_hot_data`[.drop( )](https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.drop.html)."
    ]
   },
   {