Joint study on the contribution of transitional justice to the prevention of gross violations and abuses of human rights and serious violations of international humanitarian law, including genocide, war crimes, ethnic cleansing and crimes against humanity, and their recurrence : report of the Special Rapporteur on the Promotion of Truth, Justice, Reparation and Guarantees of Non-Recurrence and the Special Adviser to the Secretary-General on the Prevention of Genocide : note / by the Secretariat