This is the Markdown (e.g. README.md) preview using the API of Github.
(add-to-list 'load-path "/full/path/where/markdown-preview.el/in/")
(autoload 'mp-preview "markdown-preview" "Github flavored markdown preview for Emacs" t)
Execute M-x mp-preview while editing the Markdown.
For example README.md.html is created that it is being edited the README.md.