If you’re heading down to Nationals Park tonight to watch the team face the Mets at 7:10 p.m., you might like to know that you suddenly have a new option in terms of transportation: you can actually just drive and pay $15-$20 to park when you get there. WTOP first reported this policy change late on Monday. Before today, you had to be a season ticket holder or buy game day parking permits online beforehand…