fix etcdctl member add command

README.md

@@ -87,7 +87,9 @@ cluster:
 6. Set up the remaining machines. It is a two-step process: first, run
    the following command on the first machine:
 
-        $ etcdctl member add machine2 http://machine2:2380/
+        $ etcdctl member add machine2 http://machine2:2380
+
+    (remember not to include a final slash on the node URL).
 
     This will print out some environment variables. You should copy
     the `ETCD_INITIAL_CLUSTER` line into `/etc/default/etcd` on