Fix minor doc errors.

www/tutorial/nscommands.html

@@ -438,7 +438,7 @@ tb-set-lan-loss $lan1 0.3
 <pre>
 tb-set-node-lan-delay <i>node</i> <i>lan</i> <i>delay</i>
 
-tb-set-node-lan-delay $lan0 $node0 40ms
+tb-set-node-lan-delay $node0 $lan0 40ms
 </pre>
 
 <dl>
@@ -474,7 +474,7 @@ tb-set-node-lan-delay $lan0 $node0 40ms
 <pre>
 tb-set-node-lan-bandwidth <i>node</i> <i>lan</i> <i>bandwidth</i>
 
-tb-set-node-lan-bandwidth $lan0 $node0 20Mb
+tb-set-node-lan-bandwidth $node0 $lan0 20Mb
 </pre>
 
 <dl>
@@ -501,7 +501,7 @@ tb-set-node-lan-bandwidth $lan0 $node0 20Mb
 <pre>
 tb-set-node-lan-loss <i>node</i> <i>lan</i> <i>loss</i>
 
-tb-set-node-lan-loss $lan0 $node0 0.05
+tb-set-node-lan-loss $node0 $lan0 0.05
 </pre>
 
 <dl>