Add Python standard readme

Author: Tim Martinak

standard-integration/server/python/README.md

@@ -35,7 +35,7 @@ PayPal Standard Integration sample in Python using Flask
 1. **Run the server**
 
    ```sh
-   flask --app server run
+   flask --app server run --port 8080
    ```
 
-1. Go to [http://localhost:8080/](http://localhost:8080/)
+1. Go to [http://localhost:8080/](http://localhost:8080/)