Hello Chris
This is a good point you bring up. The lesson is referring to commands that are used in Cisco IOS devices such as routers. The links that I provided were of a command reference document for QoS commands of IOS systems. The document that you shared is of the ASR 9000 running the IOS XR version 4.0.0. This provides a slightly different set of commands and syntax for QoS. In the IOS XR 4.0.0 the command police rate is used to police data plane traffic. This is also the reason why the syntax ofpolice rate 10 mbps did not work in the IOS version that you tried.
This brings up a good point because it allows us to see some of the different IOS versions that are available for devices today and how they can sometimes be different based on the type (IOS or IOS XR), the version or the platform. Such differences are even more pronounced for systems such as ASAs.
I hope this has been helpful!
Laz