add Vincent's version of the happiness dataset, update links after BertrandÅ's...

add Vincent's version of the happiness dataset, update links after BertrandÅ's changes in the file structure

notebooks/Courses/scipy_material.py

@@ -28,7 +28,7 @@ def illustration_confidence_interval(m=46, s=1, alpha=0.05):
     plt.axhline(0, color='k', linestyle=':', linewidth=1)
     plt.xlabel('population mean')
     plt.ylabel('probability density')
-    plt.axvline(m, color='k', linestyle=':', linewidth=1, label='sample mean')
+    plt.axvline(m, color='g', linestyle=':', linewidth=1, label='sample mean')
 
     u = stats.norm().isf(alpha / 2)
     ci_low = m - u * s