Update documentation to describe how to install etcd for testing

docs/devel/development.md

@@ -264,7 +264,9 @@ Coverage results for the project can also be viewed on [Coveralls](https://cover
 
 ## Integration tests
 
-You need an [etcd](https://github.com/coreos/etcd/releases/tag/v2.0.12) in your path, please make sure it is installed and in your ``$PATH``.
+You need an [etcd](https://github.com/coreos/etcd/releases) in your path. To download a copy of the latest version used by Kubernetes, either
+ * run `hack/install-etcd.sh`, which will download etcd to `third_party/etcd`, and then set your `PATH` to include `third_party/etcd`.
+ * inspect `cluster/saltbase/salt/etcd/etcd.manifest` for the correct version, and then manually download and install it to some place in your `PATH`.
 
 ```sh
 cd kubernetes