Trivial: Reorder doc of "server shelve" command to keep alphabetic order.

Change-Id: I616154a8c958b6980233014c7ae1c4544283d72d

Author: tang-chen

doc/source/command-objects/server.rst

@@ -508,21 +508,6 @@ Resume server(s)
 
     Server(s) to resume (name or ID)
 
-server shelve
--------------
-
-Shelve server(s)
-
-.. program:: server shelve
-.. code:: bash
-
-    os server shelve
-        <server> [<server> ...]
-
-.. describe:: <server>
-
-    Server(s) to shelve (name or ID)
-
 server set
 ----------
 
@@ -555,6 +540,21 @@ Set server properties
 
     Server (name or ID)
 
+server shelve
+-------------
+
+Shelve server(s)
+
+.. program:: server shelve
+.. code:: bash
+
+    os server shelve
+        <server> [<server> ...]
+
+.. describe:: <server>
+
+    Server(s) to shelve (name or ID)
+
 server show
 -----------