Update Prior and Posterior Bugs graph

The graph is misleading since the y axis maximum is 0.9 - the y axis should be [0.0-1.0] to better reflect that the left and right values are inverses of each other.

Author: monkpit

Chapter1_Introduction/Chapter1.ipynb

@@ -360,6 +360,8 @@
     "        label=\"posterior distribution\",\n",
     "        lw=\"3\", edgecolor=colours[1])\n",
     "\n",
+    "axes = plt.gca()",
+    "axes.set_ylim([0,1])",
     "plt.xticks([0.20, .95], [\"Bugs Absent\", \"Bugs Present\"])\n",
     "plt.title(\"Prior and Posterior probability of bugs present\")\n",
     "plt.ylabel(\"Probability\")\n",