Ask HN: Do you have a project component library/style-guide

Most projects have reusable ui components but the project I've most recently started work on has a section devoted to a 'component gallery' with documentation on how they should be used. Highly useful but the first time I've come across this sort of thing outside of the documentation explicitly for ui frameworks. Has anyone else worked on a project with anything like this? I think it's a great way to tie-in documentation for devs.