Update notebook

Author: hamidkm9

notebooks/demo_linearboost_usage.ipynb

@@ -992,6 +992,13 @@
     "\n"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "**CatBoost results:**"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 57,