doc: fix typo in doc/node.1

PR-URL: https://github.com/nodejs/node/pull/4680
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/node.1

@@ -100,7 +100,7 @@ value to an empty string ("") disables persistent REPL history.
         type: bool  default: false
   --harmony (enable all completed harmony features)
         type: bool  default: false
-  --harmony_shipping (enable all shipped harmony fetaures)
+  --harmony_shipping (enable all shipped harmony features)
         type: bool  default: true
   --legacy_const (legacy semantics for const in sloppy mode)
         type: bool  default: true