Update README.md

Should be consistent on which maven command we're using, clean package seems to be the most appropriate given it's a sample application that should only be used for demos.

Author: michaeltee

jsp-flexjs/README.md

@@ -21,7 +21,7 @@ A simple client-side tokenization example integration using Flex JavaScript SDK
 
 2. Build and run the application using maven
   ```bash
-  mvn package
+  mvn clean package
   ```
 
   This will produce a `.war` file that can be deployed to a Tomcat server instance. The deployed application will serve a demonstration card tokenization page on `http://localhost:8080/`. To serve from a different domain, ensure that `targetOrigin` domain is specified when making a call to the `/keys` endpoint. For a detailed example please see [FlexKeyProvider.java](./src/main/java/com/cybersource/example/FlexKeyProvider.java), line 47.