Merge pull request #7880 from ahardin-rh/oc-adm-drain-37

Added --dry-run option for `oc adm drain` for 3.7

Author: ahardin-rh

admin_guide/manage_nodes.adoc

@@ -285,6 +285,13 @@ is drained):
 $ oc adm drain <node1> <node2> --delete-local-data=true
 ----
 
+To list objects that will be migrated without actually performing the evacuation,
+use the `--dry-run` option and set it to `true`:
+
+----
+$ oc adm drain <node1> <node2>  --dry-run=true
+----
+
 [[rebooting-nodes]]
 == Rebooting Nodes