Use localized Documents folder on Linux instead of "~/Documents"

I use ArchLinux with a localized GNOME setup, what basicly means I dont have a ~/Documents folder by default, but instead its ~/Dokumente. I wish Unreal Engine would use the folder ~/Dokumente/Unreal Projects intead of ~/Documents/Unreal Projects .

XDG Utils on Linux are responsible for implementing something like this, in this case we need to use the command
xdg-user-dir DOCUMENTS to get the path we need: /home/gotwig/Dokumente in my case.

I sent in a PR for this issue:

I tested it locally myself, but I do not run any localizations so you will be a better test case.

I’m going to send a PR to Epic for the change, while in the mean time you can use this by editing Engine/Source/Runtime/Core/Private/Linux/LinuxPlatformProcess.cpp and replacing the UserDir method.