Added the wrong year for a metric value+example

Global_Reporting_Initiative+Hazardous_Waste_G4_EN23_a+BMW_Group+201

http://wikirate.org/BMW_Group?view=new_metric_value&project=Global%20Reporting%20Initiative%20-%20G4%20Sustainability%20Reporting%20Standards

Metric: Hazardous Waster (G4-EN23-a)