Visual Studio 2010: How to generate documentation out of code comments?

Using NDoc. The NDoc is outdated, but there is NDoc3. More alternatives

1. With a project selected in Solution Explorer, on the Project menu, click Properties.
2. Click the Build tab.
3. On the Build page, select XML documentation file. By default, the file is created under the specified output path, for example, "bin\Debug\Projectname.XML".

How to: Generate XML Documentation for a Project