Robert Cain teaches us about teaching others about something:
In my previous post, Fun With PowerShell – Authoring Help, I covered how to author comment based help for your functions.
In addition to help for your functions, it’s also possible to write
about_help. PowerShell itself contains many about topics for PowerShell itself.
These about topics are designed to provide further information for your users, information that may not fit into the confines of a functions help. These texts can be as long as you need.
I will say that the Powershell team nailed it with the way they implemented help.