The GitHub Files integration allows you to take a link to a GitHub file or a permalink to lines of code and display them into code blocks in GitBook.
How it works
After installing the GitHub Files integration, you're able to insert it into a GitBook file in the (CMD + /) menu.
Insert the integration, paste your link, and the integration will display the code in a formatted code block.
In order to view code from private repositories, you'll need to authorize with your GitHub Account in the integration's configuration page.