Adds to-do list to the begin of each manual

doc/index.rst

@@ -8,6 +8,8 @@
  Bob's Metric Routines
 =======================
 
+.. todolist::
+
 This module contains base functionality from Bob bound to Python, available in
 the C++ counter-part ``bob::measure``. It includes routines for assessing
 performance on machine learning and pattern recognition applications.