I'm reading about KID in "The Complete Book of Chess Strategy" by Jeremy Silman, and I don't understand one of his points. He gives the following moves (which is the "Averbackh Variation"):
1.d4 Nf6 2.c4 g6 3.Nc3 Bg7 4.e4 d6 5.Be2 0-0 6.Bg5 c5 7.d5 Qa5 8.Bd2 e6
Which he says (of Black's plan) "...opening the e-file for his Rooks". But I don't see that. There's no way white would go 9.exd6 when 9.exf6 is there, unless we are talking a Knight sacrifice with 9.exf6 exf6. But even then, the e-file is not totally open with a Bishop at e2.
So I guess my question is if I'm reading that right, or if there is maybe some typo/error here. Black sacrifices his Knight for a partially open e-file?