Ah, getting it from Lakka can be a bit of a hassle, so no hard feelings if you decide not to bother with it 
But, here we go:
You’ll need to SSH in from another machine and navigate to your autoconfig directory (look in settings > directory to find out what it’s set to). The one you made should be inside the udev directory, and the easiest way to find out which one is yours is probably going to be to just compare with the repo and see which one isn’t already there. You can open it with nano and then copy/paste the contents to your local machine or however else you want to get it off of your Lakka machine.
Once that’s done, go over to the github repo and look in the upper-right corner of your browser window to find the ‘fork this repo’ button. This will make a copy of the repo under your account. Once it’s finished forking, you should be looking at your copy of the repo. Navigate into the ‘udev’ directory and click the button to ‘create a new file’.
Name it after your newly-created autoconfig file and then copy/paste the contents from your file into it. It’s not strictly necessary, but we also ask that you include the button labels (look at some of the other files in the repo to see how that looks), so the pad’s buttons will be properly named in the core input remapping menu.
Once your autoconfig is all pasted in, save the file with an informative commit message and then head up to the ‘pull requests’ tab at the top of your repo. It will walk you through the process of submitting your changes back to the libretro repo.
That’s a lot of steps, I know, including creating an account at github, so it’s no big deal if you don’t want to go through the trouble. I’m also willing to submit it for you if you just want to paste it here (that is, to save yourself from dealing with github).
