Completed minimal sample in JsDoc of stock client.

src/node/examples/stock_client.js

@@ -39,5 +39,8 @@ var examples = grpc.load(__dirname + '/stock.proto').examples;
  *
  * var StockClient = require('stock_client.js');
  * var stockClient = new StockClient(server_address);
+ * stockClient.getLastTradePrice({symbol: 'GOOG'}, function(error, response) {
+ *   console.log(error || response);
+ * });
  */
 module.exports = examples.Stock;