why did achebe add a chapter after okonkwo's death?

Okonkwo hung himself; he wasn't killed.

Okonkwo did what he did because he knew it meant that the clans would not go to war. He gave up everything he believed for this reason, including the respect of his clan. He knew that he would be considered evil and untouchable after hanging himself (dirty), but he did it anyway.......... far all of the right reasons.