Kramdown has superseded Maruku as the default Markdown interpreter for Jekyll.
By default, Jekyll sites on GitHub Enterprise Pages rely on a program called Kramdown to interpret Markdown. Jekyll used to use a program called Maruku to achieve this, but in October 2012 the maintainers of Maruku announced that they were shutting down the project. Maruku is now considered obsolete. Builds with invalid Markdown or HTML syntax may unexpectedly fail if you are using Maruku as your Markdown interpreter.
Upgrading to Kramdown
If you've had a GitHub Enterprise Pages site for a long time, you'll need to upgrade to the new Markdown interpreter. You can upgrade by adding the following to your site's _config.yml file:
markdown: kramdown
This will tell GitHub Enterprise Pages to use the Kramdown Markdown interpreter instead of Maruku. You may also choose to use another interpreter such as Redcarpet; however, those upgrading from Maruku may find Kramdown to be a better fit.
Differences between Kramdown and Maruku
Kramdown is syntactically almost identical to Maruku in its implementation of Markdown. If you're new to Kramdown, or just want to brush up on your Markdown, you can check out the quick reference guide or the full documentation. That said, there are a few gotchas—generally highlighted in yellow within the syntax guide.
