Ahaggar: update the README file with aims and requirements

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: output_base_copy() will now require number of bytes to copy

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
Ahaggar: Update the output_base_copy() to handle number of bytes to copy

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>