ad·den·dum 
/əˈdɛndəm/ noun
plural ad·den·da /əˈdɛndəm/ noun /-ˈdɛndə/ or ad·den·dums [count] : something that is added ; especially : a section of a book that is added to the main or original text
▪ The letters are included as an addendum to the biography.
▪ The letters are included as an addendum to the biography.
