Fix trace_plot method

Author: canyon289

notebooks/04-instructor-multi-group-comparsion-sterilization.ipynb

@@ -225,7 +225,7 @@
    "outputs": [],
    "source": [
     "# Plot the trace plots.\n",
-    "az.traceplot(trace)"
+    "az.plot_trace(trace)"
    ]
   },
   {