addressed review comments - grammar corrections, space additions

src/doc/book/vectors.md

@@ -114,30 +114,37 @@ for i in v {
     println!("Take ownership of the vector and its element {}", i);
 }
 ```
-Note: You cannot use the vector again once you have iterated with ownership of the vector.
-You can iterate the vector multiple times with reference iteration. For example, the following
-code does not compile.
+
+Note: You cannot use the vector again once you have iterated by taking ownership of the vector.
+You can iterate the vector multiple times by taking a reference to the vector whilst iterating. 
+For example, the following code does not compile.
+
 ```rust
 let mut v = vec![1, 2, 3, 4, 5];
+
 for i in v {
     println!("Take ownership of the vector and its element {}", i);
 }
+
 for i in v {
     println!("Take ownership of the vector and its element {}", i);
 }
 ```
+
 Whereas the following works perfectly,
 
 ```rust
 let mut v = vec![1, 2, 3, 4, 5];
+
 for i in &v {
-    println!("A mutable reference to {}", i);
+    println!("This is a reference to {}", i);
 }
 
 for i in &v {
-    println!("A mutable reference to {}", i);
+    println!("This is a reference {}", i);
 }
 ```
+
 Vectors have many more useful methods, which you can read about in [their
 API documentation][vec].