Sometimes even including a readme file isn't even standard. In rebuilding my runtimes after my disastrous start to 2017, I've found quite a few store products that didn't even have a readme file (which is really unprofessional).
For those looking for an app that can list files in a product runtime, EvilInnocence has "Poser Product Checker." It's free, and in addition to making lists, it checks for path length (I think that's for Mac), absolute paths, missing files, and incomplete paths. I don't know if it's okay to link to it, since it's at a store. Just Google "EvilInnocence Poser Product Checker."
Poser Product Checker has been very handy, in addition to Dimension3D's Runtime Repair, while I'm working on rebuilding my runtimes. I organize thing the way I want in a empty folder on the desktop, put all of the documentation in a Readme folder named for the product, do any editing that I know I need to do (usually when those darn .pmd files are in the runtime content folders like Characters or Props) , run Runtime Repair and fix anything it pops on (if it's fixable). Then I run Poser Product Checker, and check that it doesn't zero in on any problems that Runtime Repair didn't (sometimes it does when it comes to shortened or incomplete paths). I copy the File List from Poser Product Checker into a document in the readme folder. Then, I rezip my new runtime, and install it whatever external runtime will be it's new home.