used curly instead of straight quotes

Author: jonmarkprice

src/doc/book/ownership.md

@@ -212,7 +212,7 @@ But, unlike a move, we can still use `v` afterward. This is because an `i32`
 has no pointers to data somewhere else, copying it is a full copy.
 
 All primitive types implement the `Copy` trait and their ownership is
-therefore not moved like one would assume, following the 'ownership rules'.
+therefore not moved like one would assume, following the ‘ownership rules’.
 To give an example, the two following snippets of code only compile because the
 `i32` and `bool` types implement the `Copy` trait.