Update documentation to mention different kernel drivers and their special files

[ndim]

https://github.com/spkr-beep/beep/issues/25 pointed out that the documentation never says which driver to load. This affects more than one documentation file, so this issue tracks what the partial documentation rewrite needs to address.

• [ ] The Linux kernel contains more than one driver implementing the EV_SND/SND_TONE evdev API. Userspace implementations are also possible.
• [ ] Every kernel driver produces a hardware specific well known device aliases (mention some of them.
• [x] udev will create devices and well known device aliases
• [x] how to re-run udev to create device aliases like a system reboot does
• [x] how to use lsmod and modprobe to ensure a driver is loaded in case udev does not work
• [ ] README.md should mention the Linux drivers
• [ ] PERMISSIONS.md needs adaptations (well known names)

[ndim]

Moved the non-pcspkr stuff into the post-1.4.10 realm.