Quick start guide: fix links to images (#8072)
Quick start guide: fix links to images (#8072)

"../resources/..." was not working on some devices like
Android. Build the correct relative path on all devices.
koreader/koreader,Frenzie/koreader,poire-z/koreader,koreader/koreader,NiLuJe/koreader,NiLuJe/koreader,Frenzie/koreader,poire-z/koreader