PowerShell's Get-Help gives you documentation for one cmdlet at a time but it does not provide any means to document your API in its entirety. DocTreeGenerator fills that niche. Once you have instrumented your modules with doc-comments to satisfy Get-Help, you need surprisingly little extra work for DocTreeGenerator to produce a comprehensive, hyperlinked documentation tree (in the form of a collection of web pages).

When you create your library code, whether it is in PowerShell or in C#, you need to add documentation comments (doc-comments for short) that may then be automatically extracted and formatted to generate some documentation. If you are writing in PowerShell, those doc-comments are processed directly by PowerShell when you invoke Get-Help on your cmdlet. If you are writing in C#, you need to use a third party tool to pre-process your doc-comments into a form that Get-Help can use--I highly recommend XmlDoc2CmdletDoc for this purpose. It reduces what used to be a tedious and difficult task of documenting C# cmdlet libraries to the same effort needed for documenting PowerShell cmdlets--just add appropriate doc-comments in your C# code.

Beyond those standard doc-comments instrumenting your code, for DocTreeGenerator to do its job you need to provide just a few summary files as well and perhaps tweak the HTML or CSS in the template to get the look and feel you want.

To start with the big picture, this is a thumbnail (albeit a large one!) illustrating the complete solution for documenting PowerShell APIs. Note that besides DocTreeGenerator, this also includes the other crucial 3rd party tool you need, XmlDoc2CmdletDoc.

Download the full wallchart in a convenient PDF from my article on Simple-Talk.com: Unified Approach to Generating Documentation for PowerShell Cmdlets.

1. If you have Windows 10 or later (or have updated your PS 3 or 4 environment with PowerShellGet), you can just run Install-Module -Name DocTreeGenerator to install this module from the PowerShell Gallery. Otherwise, you can download it from GitHub. After downloading, unzip DocTreeGenerator-master.zip into your PowerShell Modules directory ($env:UserProfile\Documents\WindowsPowerShell\Modules) and drop the "-master" suffix on the extracted folder.
2. Import the module in your profile or import it manually: Import-Module DocTreeGenerator

See extensive help available from Get-Help Convert-HelpToHtmlTree and Get-Help Publish-ModuleDocumentationTree. Also see some practical examples and detailed notes on how to use it on Simple-Talk.com: How To Document Your PowerShell Library

You can see a real-world example of its use on my open source website, showing a tree complete with an index to all functions and modules: CleanCode PowerShell Libraries And adjacent to this "readme" file is a rendering of the help for Convert-HelpToHtmlTree itself (Convert-HelpToHtmlTree.html).

DocTreeGenerator uses the output of Get-Help as its input; some of the vagaries of Get-Help can be compensated for, but not always. Known issues are itemized below. The designation [PS] applies to cmdlets written in PowerShell, while [C#] applies to cmdlets written in C#.

Other issues in this section are things to watch out for that might cause undo consternation.

[PS] You cannot have a preformatted block immediately following an example (a tab or 4+ leading spaces signals a preformatted line). If you do, the first line--in this example the column headers--will not be preformatted. (You can observe this problem if you just run Get-Help for your cmdlet on the command-line.)

============ EXCERPT FROM A PS DOC-COMMENT SECTION ============================
.EXAMPLE
PS> Show-Packages .\default.proj
	Name              DependsOnTargets        CallTarget
	----              ----------------        ----------
	All                                       Clean;RestorePackages;Build
	Test              UnitTest;IntegrationTest
	Analyze
===============================================================================

Remedy: Add a regular text paragraph between the line of code and the start of the preformatted block:

============ EXCERPT FROM A PS DOC-COMMENT SECTION ============================
.EXAMPLE
PS> Show-Packages .\default.proj
This line could say anything; mainly it is to fix Get-Help's formatting issue!
	Name              DependsOnTargets        CallTarget
	----              ----------------        ----------
	All                                       Clean;RestorePackages;Build
	Test              UnitTest;IntegrationTest
	Analyze
===============================================================================

[PS,C#] If you start a line with an asterisk, plus, or minus, you are asking to force a line break. (Presumably you are enumerating items in a list.) But watch out that you do not do this inadvertantly. (If, for example, you are talking about code you might mention a "-Force" option--just make sure that is not the first thing on the line, otherwise it will end the paragraph prematurely at that point.)

[PS,C#] If you start a line with a space, this also forces a line break. This is very useful, for example, if you want example code to span multiple lines in the HTML rendered output. Use a couple leading spaces on each line after the first that you want to start on a new line. (But do NOT use more than 3--otherwise you trigger generating a pre-formatted block, which is likely not what you want.)

[PS,C#] Also useful for code examples: start a line with "PS>", i.e. a canonical PowerShell prompt, and this also forces a line break. Thus, if you want to show multiple separate commands, start each line with "PS>". (Contrast that with if you want to show multiple piped commands, just use a leading space or two on each line per the previous point above.