Google Drive is Google's file sync app that lets you store all of your files online alongside your Google Docs documents, and keep them synced with all of your devices.
Open a new review when approved copy changes before publication.
Your content lead gets a new review of revised copy, with the changes and publishing checks in one place before publication.
File each formatted draft in the review folder and reply to its writer.
Your writer's Markdown draft becomes a formatted Google Doc in your review folder, with comment access and a link in the original email thread.