separated modules into diff files

ch07/restaurant/src/front_of_house.rs

@@ -0,0 +1 @@
+pub mod hosting;

ch07/restaurant/src/front_of_house/hosting.rs

@@ -0,0 +1 @@
+pub fn add_to_waitlist() {}

ch07/restaurant/src/lib.rs

@@ -1,8 +1,4 @@
-mod front_of_house {
-    pub mod hosting {
-        pub fn add_to_waitlist() {}
-    }
-}
+mod front_of_house;
 
 pub use crate::front_of_house::hosting;