It is a best practice for PowerShell modules to contain help topics

A module must contain the following help depending on the type of the module:

Cmdlet Help. The Help topics that describe cmdlets in a module are XML files that use the command help schema. For more information about writing cmdlet Help, see Writing Windows PowerShell Cmdlet Help.

Provider Help. The Help topics that describe providers in a module are XML files that use the provider help schema. For information about writing provider Help files, see Writing Windows PowerShell Provider Help.

Function Help. The Help topics that describe functions in a module can be XML files that use the command help schema or comment-based Help topics within the function, or the script or script module. For more information about comment-based Help, see about_Comment_Based_Help.

Script Help. The Help topics that describe scripts in a module can be XML files that use the command help schema or comment-based Help topics in the script or script module. For more information about comment-based Help, see about_Comment_Based_Help

Conceptual ("About") Help. You can use a conceptual ("about") Help topic to describe the module and its members and to explain how the members can be used together to perform tasks. Conceptual Help topics are text files with Unicode (UTF-8) encoding. The file name must use the about_.help.txt format, such as about_MyModule.help.txt. By default, Windows PowerShell includes over 100 of these conceptual About Help topics, and they are formatted like the following example.

https://msdn.microsoft.com/en-us/library/dd878343(v=vs.85).aspx