Planning Scene/C++ API Tutorial missing part

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Hi, as I was reading this tutorial (sorry but I don't have enough karma to post a real link):

xxxx://docs.ros.org/api/pr2_moveit_tutorials/html/planning/src/doc/planning_scene_tutorial.html

I saw that the right way to maintain current planning scene is to use the PlanningSceneMonitor:

The PlanningSceneMonitor is the recommended method to create and maintain the current planning scene (and is discussed in detail in the next tutorial)

But I haven't find in any of the other Moveit tutorials any reference to that class. Maybe I'm looking in the wrong place? Tx