Fix typo in osc doc

Change-Id: I8df73b36378e3de88ebe6d1ec125546c83f707c7

Author: LiuNanke

doc/source/command-objects/network-agent.rst

@@ -49,7 +49,7 @@ Set network agent properties
         [--enable | --disable]
         <network-agent>
 
-.. option:: --description <discription>
+.. option:: --description <description>
 
     Set network agent description