Yes and no.
Workaround we used: You can upload a file(s) to course files and link to it there from within the html editor of the assignment. Find the file in course files folder and right-click it, choose properties and copy the address location. Edit your assignment and past the link to the appropriate place using the editor's link options.
Alternative: I think workshop allows an uploaded file to be displayed and can work similarly to assignment with a little work.