Serving your content up to readers is redistributing it. You are implicitly granting Github that right by agreeing to let them serve your content to other users

Serving your content up to readers is redistributing it. You are implicitly granting Github that right by agreeing to let them serve your content to other users. Note that Github isn't in the user generated content business, primarily, so they are less at risk by leaving the terms loose and human. I would generally prefer Medium's terms, but written / translated into non-legalese. Some company did this a few years ago, I wish I could find it.