Update expressroute-routing.md

Author: derekolo

articles/expressroute/expressroute-routing.md

@@ -281,6 +281,7 @@ In addition to the BGP tag for each region, Microsoft also tags prefixes based o
 | China East | 12076:51302 |
 | China East 2| 12076:51303 |
 | China North 2 | 12076:51304 |
+| China North 3 | 12076:51305 |
 
 | **Service in National Clouds** | **BGP community value** |
 | --- | --- |