Adds use case to USECASES.md

It is a use case listed in https://wiki.openstack.org/wiki/Puppet-
openstack/ceph-blueprint and it would be a useful example when
considering what the puppet-ceph module can do. It must be linked
from the README.md

Closes-Bug: #1243331
Change-Id: I6d477353a0e1bc00eef77e96099e92845f47f21f

README.md

@@ -37,6 +37,7 @@ Limitations
 Use Cases
 ---------
 
+* [I want to try this module, heard of ceph, want to see it in action] (USESCASES.md#i-want-to-try-this-module,-heard-of-ceph,-want-to-see-it-in-action)
 * [I want to operate a production cluster] (USECASES.md#i-want-to-operate-a-production-cluster)
 
 Development

USECASES.md

@@ -1,3 +1,31 @@
+Use Cases
+=========
+
+I want to try this module, heard of ceph, want to see it in action
+------------------------------------------------------------------
+
+_Notice : Please note that the code below is a sample which may not be up to date and is not expected to work._
+
+I want to run it on my own laptop, all in one. The **ceph::conf** class will create configuration file with no authentication enabled, on my **localhost**. The **ceph::mon** resource configures and runs a monitor to which two **ceph::osd** daemon will connect to provide disk storage, using directories in **/srv** on the laptop.
+
+    /node/ {
+
+      class { 'ceph::conf':
+        auth_enable => false,
+        mon_host    => 'localhost'
+      }
+
+      ceph::mon { $hostname: };
+      ceph::osd { '/srv/osd1': };
+      ceph::osd { '/srv/osd2': };
+
+    }
+
+* install puppet,
+* paste this in site.pp and replace /node/ with the name of your current node,
+* puppet apply site.pp,
+* type **ceph -s** : it will connect to the monitor and report that the cluster is **HEALTH_OK**
+
 I want to operate a production cluster
 ---------------------------------------