docs: remove mention of topology file to grow a cluster

The topology file is not a reliable way to add nodes & devices to an existing cluster, remove mention of that method from the maintenance doc.

docs/admin/maintenance.md

@@ -92,27 +92,6 @@ $ heketi-cli device add \
 Device added successfully
 ```
 
-A much easier way is to expand a cluster is to add a new node to your
-topology file file. When adding the new node you **must** add this node
-information after the existing ones so that the Heketi cli figures out
-which cluster this new node should be part of. Here is an example:
-
-```
-...
-        Found node 192.168.10.103 on cluster 3e21671bc4f290fca6bce464ae7bb6e7
-                Found device /dev/sdb
-                Found device /dev/sdc
-                Found device /dev/sdd
-                Found device /dev/sde
-                Found device /dev/sdf
-                Found device /dev/sdg
-                Found device /dev/sdh
-                Found device /dev/sdi
-        Creating node 192.168.10.105 ... ID: be0e8f7fba6ec1e5aa0337141f356013
-                Adding device /dev/sdb ... OK
-                Adding device /dev/sdc ... OK
-```
-
 ## Adding a new cluster
 
 Storage capacity can also be increased by adding new clusters of GlusterFS.