I'm searching for a single center listing updates to Workflow Manager and Service Bus but haven't found one to date.  I've looked throughout the extensive documentation presented at the Workflow Manager site on MSDN and didn't find a single page focused on updating the Workflow Manager framework.  Neither the SharePoint Updates center nor the SharePoint 2013 Workflow Resource Center provide any guidance regarding the essential maintainance task of updating Workflow Manager.  There isn't even a forum devoted to Workflow Manager or Service Bus.  Does a central location devoted to updating Workflow Manager even exist? 

Download the Web Platform installer.  Any updates available for Workflow Manager and Service Bus will show up there if you ask to install Workflow Manager.

https://www.microsoft.com/web/downloads/platform.aspx