README.md: Remove the unprotected change example since it would actually need external synchronization

Author: patrickmn

README.md

@@ -75,29 +75,6 @@ func main() {
 		foo := x.(*MyStruct)
 			// ...
 	}
-
-	// If you store a reference type like a pointer, slice, map or channel, you
-	// do not need to run Set if you modify the underlying data. The cached
-	// reference points to the same memory, so if you modify a struct whose
-	// pointer you've stored in the cache, retrieving that pointer with Get will
-	// point you to the same data:
-	foo := &MyStruct{Num: 1}
-	c.Set("foo", foo, cache.DefaultExpiration)
-	// ...
-	x, _ := c.Get("foo")
-	foo := x.(*MyStruct)
-	fmt.Println(foo.Num)
-	// ...
-	foo.Num++
-	// ...
-	x, _ := c.Get("foo")
-	foo := x.(*MyStruct)
-	foo.Println(foo.Num)
-
-	// will print:
-	// 1
-	// 2
-
 }
 ```