rustlings vec primitive types

solutions/00_intro/intro1.rs

@@ -0,0 +1,5 @@
+fn main() {
+    // Congratulations, you finished the first exercise 🎉
+    // As an introduction to Rustlings, the first exercise only required
+    // entering `n` in the terminal to go to the next exercise.
+}

solutions/00_intro/intro2.rs

@@ -0,0 +1,4 @@
+fn main() {
+    // `println!` instead of `printline!`.
+    println!("Hello world!");
+}