docs(ec2): add CLI key import, explicit chdir

Author: Gabriel Monroy

contrib/ec2/README.md

@@ -22,7 +22,7 @@ Default output format [None]:
 Generate and upload a new keypair to AWS, ensuring that the name of the keypair is set to "deis".
 ```console
 $ ssh-keygen -q -t rsa -f ~/.ssh/deis -N '' -C deis
-$ aws ec2 import-key-pair --key-name deis --public-key-material file://~/.ssh/id_rsa.pub
+$ aws ec2 import-key-pair --key-name deis --public-key-material file://~/.ssh/deis
 ```
 
 ## Customize cloudformation.json

contrib/ec2/cloudformation.json

@@ -2,5 +2,9 @@
     {
         "ParameterKey":     "KeyPair",
         "ParameterValue":   "deis"
+    },
+    {
+        "ParameterKey":     "DiscoveryURL",
+        "ParameterValue":   "https://discovery.etcd.io/06f9b54a2ffe65f072109924604b4cd7"
     }
 ]