Add documentation of the Mok variables
Add documentation of the Mok variables

Brief overview of the function and format of the various variables used
by Shim and MokManager.

android-ia/platform_external_uefi_shim,CyanogenMod/android_external_uefi_shim,android-ia/platform_external_uefi_shim,rhinstaller/shim,CyanogenMod/android_external_uefi_shim,rhinstaller/shim,android-ia/platform_external_uefi_shim,rhinstaller/shim,CyanogenMod/android_external_uefi_shim