Update README.md with note for the example
This adds a note that the example currently does not work with the `iron` version released on crates.io.
@@ -9,6 +9,8 @@ Iron
## Response Timer Example
+Note: This example works with the current `iron` code in this repository (master branch). If you are using `iron` 0.6 from crates.io, please refer to the [corresponding example](https://github.com/iron/iron/blob/0.6-maintenance/README.md) in the branch [0.6-maintenance](https://github.com/iron/iron/tree/0.6-maintenance).
+
```rust
extern crate iron;
extern crate time;
