Remove "I AM NOT DONE" and the verify mode and add AppState

exercises/00_intro/intro2.rs

@@ -5,8 +5,6 @@
 // Execute `rustlings hint intro2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     printline!("Hello there!")
 }