Clean up and unify exercises

exercises/00_intro/intro1.rs

@@ -1,5 +1,3 @@
-// intro1.rs
-//
 // We sometimes encourage you to keep trying things on a given exercise, even
 // after you already figured it out. If you got everything working and feel
 // ready for the next exercise, remove the `I AM NOT DONE` comment below.
@@ -8,9 +6,6 @@
 // reloaded when you change one of the lines below! Try adding a `println!`
 // line, or try changing what it outputs in your terminal. Try removing a
 // semicolon and see what happens!
-//
-// Execute `rustlings hint intro1` or use the `hint` watch subcommand for a
-// hint.
 
 fn main() {
     println!("Hello and");

exercises/00_intro/intro2.rs

@@ -1,9 +1,4 @@
-// intro2.rs
-//
 // Make the code print a greeting to the world.
-//
-// Execute `rustlings hint intro2` or use the `hint` watch subcommand for a
-// hint.
 
 fn main() {
     printline!("Hello there!")