Update "use" subchapter to 2018 Edition syntax

Author: codesections

src/mod/use.md

@@ -6,7 +6,7 @@ access. It is often used like this:
 ```rust,editable,ignore
 // extern crate deeply; // normally, this would exist and not be commented out!
 
-use deeply::nested::{
+use crate::deeply::nested::{
     my_first_function,
     my_second_function,
     AndATraitType
@@ -43,7 +43,7 @@ fn main() {
     {
         // This is equivalent to `use deeply::nested::function as function`.
         // This `function()` will shadow the outer one.
-        use deeply::nested::function;
+        use crate::deeply::nested::function;
         function();
 
         // `use` bindings have a local scope. In this case, the