It's true. Barring criminal activity or a terrible personal statement, you should get in almost everywhere with those numbers.
I think it was a wise choice not to have an addendum. No offense but having done so might make you seem like a nitpicky a$$.
The admissions committee will be impressed with your work and if they are really curious as to why your GPA is lower than it should appear, they will be able to see where that low grade comes from. High school is generally irrelevant once you've left it.
Good luck, you should have very few problems.