Revise paste Retroarch Quick Setup Guide

#quick retroarch setup on Debian Linux

sudo apt install retroarch

# get roms
mkdir -p ~/roms/{nes,mame,gameboy,sega}
wget "https://archive.org/download/mame-merged/BIOS/MAME%20%28bios-devices%29.zip/MAME%20%28bios-devices%29%2Fqsound_hle.zip" -cO ~/roms/mame/qsound_hle.zip
wget "https://archive.org/download/mame-merged/mame-merged/sfa2.zip" -cP ~/roms/mame
wget -cP ~/roms/mame  "https://archive.org/download/mame-merged/mame-merged/mspacman.zip"

wget -cP ~/roms/nes  "https://archive.org/download/nes-romset-ultra-us/Super%20Mario%20Bros.%20%2B%20Duck%20Hunt%20%28U%29%20%5B%21%5D.zip"
wget -cP ~/roms/nes  "https://archive.org/download/nes-romset-ultra-us/Super%20Mario%20Bros.%203%20%28USA%29%20%28Rev%201%29%20%28Virtual%20Console%29.zip"
wget -cP ~/roms/nes  "https://archive.org/download/nes-romset-ultra-us/Super%20Mario%20Bros.%202%20%28U%29%20%28PRG1%29%20%5B%21%5D.zip"

wget -cP ~/roms/gameboy  "https://archive.org/download/game-boy-romset-ultra-us/Tetris%20%28World%29%20%28Rev%20A%29.zip"
wget -cP ~/roms/gameboy  "https://archive.org/download/game-boy-romset-ultra-us/Super%20Mario%20Land%20%28World%29.zip"

wget -cP ~/roms/sega  "https://archive.org/download/sega-genesis-romset-ultra-usa/Sonic%20The%20Hedgehog%20%28USA%2C%20Europe%29.zip"
wget -cP ~/roms/sega  "https://archive.org/download/sega-genesis-romset-ultra-usa/Sonic%20The%20Hedgehog%202%20%28USA%2C%20Europe%29%20%28Rev%20A%29%20%28Virtual%20Console%29.zip"

#start retroarch
Settings -> User Interface  -> Menu Item Visibility -> Show "Core Downloader"
Main Menu -> Online Updater -> Update All

#Load Cores
Load Core -> Download Cores -> Select Cores (use 's' to search)

#if cores will not download check permissions
sudo chmod 777 /usr/lib/x86_64-linux-gnu/libretro

#Create Playlists
Import Content -> Scan Directory

#get thumbnails
Main Menu -> Online Updater -> Playlist Thumbnail Updater
Main Menu -> Online Updater -> On-Demand Thumbnail Downloader (if you want to download as you go)

#mame playlist and thumbnails
#mame is special
#dat file needed.  It's an xml file, but you need to rename it .dat
wget -cO ~/roms/mame.dat "https://raw.githubusercontent.com/libretro-thumbnails/mame2003-plus-thumbnail-sources/master/MAME%202003-Plus%20-%202018-12-31.xml"

Import Content -> Manual Scan

#Manual Thumbnails
Main Menu -> Show Desktop Menu
#thumbnail images can be found here:
https://thumbnails.libretro.com/