Hi! I am using Org-mode files for READMEs and stuff on github.com. Since github is using an old version of org-ruby[1] to visualize Org-mode, there is only a limited support for Org-mode syntax elements.
If you don't want to try&error by yourself, take a look at github-orgmode-tests[2] where you can see, what works and what doesn't work (yet). HTH 1. https://github.com/bdewey/org-ruby 2. https://github.com/novoid/github-orgmode-tests -- Karl Voit