Fix rolling restart documentation

The change was discussed here: https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!msg/elasticsearch/CtuK7VToOak/FpDYkcJ6OgAJ

Closes #285

Author: ichernev

520_Post_Deployment/40_rolling_restart.asciidoc

@@ -24,7 +24,7 @@ The procedure is as follows:
 help speed up recovery time.
 
 2. Disable shard allocation.  This prevents Elasticsearch from rebalancing
-missing shards until you tell it otherwise.  If you know the maintenance will be
+missing shards until you tell it otherwise.  If you know the maintenance window will be
 short, this is a good idea.  You can disable allocation as follows:
 +
 [source,js]
@@ -59,9 +59,12 @@ PUT /_cluster/settings
 }
 ----
 +
-Shard rebalancing may take some time.  At this point, you are safe to resume
-indexing (if you had previously stopped), but waiting until the cluster is fully
-balanced before resuming indexing will help speed up the process.
+Shard rebalancing may take some time.  Wait until the cluster has returned
+to status `green` before continuing.
 
 7. Repeat steps 2 through 6 for the rest of your nodes.
 
+8. At this point you are safe to resume indexing (if you had previously stopped),
+but waiting until the cluster is fully balanced before resuming indexing will help
+to speed up the process.
+