Documenting your project with wikis
Wikis are available in public repositories with GitHub Free, and in public and private repositories with GitHub Pro, GitHub Team, GitHub Enterprise Cloud, and GitHub Enterprise Server. For more information, see "GitHub's products."
You can use a wiki to share detailed, long-form information about your project.
You can host documentation for your repository in a wiki, so that others can use and contribute to your project.
Adding or editing wiki pages
You can add and edit wiki pages directly on GitHub or locally using the command line.
Creating a footer or sidebar for your wiki
You can add a custom sidebar or footer to your wiki to provide readers with more contextual information.
Editing wiki content
You can add images and links to content in your wiki, and use some supported MediaWiki formats.
Viewing a wiki's history of changes
Because wikis are Git repositories, every change you make is a commit that you can view.
Changing access permissions for wikis
Only repository collaborators can edit a public repository's wiki by default, but you can allow anyone with a GitHub to edit your wiki.
You can disable your repository's wiki.