block: Add sysfs documentation for the discard topology parameters
block: Add sysfs documentation for the discard topology parameters

Add documentation for the discard I/O topology parameters exported in
sysfs.

Signed-off-by: Martin K. Petersen <0384aaef27f06874adbdb09a807bb339f4aff9fd@oracle.com>
Signed-off-by: Jens Axboe <08e836a620179c237f631ad0545a7ebdf54201f3@fusionio.com>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs