If you have an older PC (laptop) with a newer OS (Windows 8/8.1), there's probably no way to get OpenGL enabled. This is at least true for my 4-year-old Lenovo ThinkPad T400s (there are no compatible drivers at MS, Lenovo or Intel site), and I suppose I am not the only one facing this compatibility problem.
Mojang now being part of Microsoft - there IS something that they (i.e. Microsoft) can do? So IMO the README text should be updated.