The addition of a glossary is the only significant 'alteration' [='change, modification'] to the book.
They did a good job on the dress 'alteration'.
He made 'alterations' in/to his will.
(..) but pleasantly confused. Well you seem in a very good mood tonight, sir. Huh, how long is this going to take me? Just a few alterations, sir. And I'll be done with your most terrifying cape yet. I'm calling it, Black Mambaaaaaaa... aaaa... aaa. Black Mamba, perfect. Ooo, gosh I am (..)2010 Megamind