done introduction

exercises/intro/intro1.rs

@@ -5,8 +5,6 @@
 // ready for the next exercise, remove the `I AM NOT DONE` comment below.
 // Execute the command `rustlings hint intro1` for a hint.
 
-// I AM NOT DONE
-
 fn main() {
     println!("Hello and");
     println!(r#"       welcome to...                      "#);

exercises/intro/intro2.rs

@@ -2,8 +2,7 @@
 // Make the code print a greeting to the world.
 // Execute `rustlings hint intro2` for a hint.
 
-// I AM NOT DONE
-
 fn main() {
-    println!("Hello {}!");
+    let str_stuff = "world";
+    println!("Hello {}!", str_stuff);
 }