fixed the few nits!

src/doc/trpl/references-and-borrowing.md

@@ -125,9 +125,9 @@ This will print `6`. We make `y` a mutable reference to `x`, then add one to
 the thing `y` points at. You’ll notice that `x` had to be marked `mut` as well,
 if it wasn’t, we couldn’t take a mutable borrow to an immutable value.
 
-You'll also notice we added an asterisk in front of `y`, making it `*y`,
-this is because y is an `&mut` reference. You'll also need to use them for
-accessing and modifying `&` references as well.
+You'll also notice we added an asterisk (`*`) in front of `y`, making it `*y`,
+this is because `y` is an `&mut` reference. You'll also need to use them for
+accessing the contents of a reference as well.
 
 Otherwise, `&mut` references are just like references. There _is_ a large
 difference between the two, and how they interact, though. You can tell