In Reedge there is a possibility to create/add general documents for each created assignment. 

In the Admin Dashboard, select  Document Library and start creating your folders and adding files. You will find the same options available in the Assignment Document section next to each folder/file. 

You will find these documents in every assignment, you can recognize them from the default documents folder because they don't have the lock icon. 

In the assignment document section, It is also possible to copy these files to other folders by clicking the 3 dots. 

Please keep in mind that you can edit and add files only and if the assignment is still open. In case you want to add additional infomation you need to open the assignement again.