add wukong (#2239)

docs/extensions.md

@@ -243,8 +243,11 @@ Check out [microbit.org](http://microbit.org/resellers/) for more information on
     "name": "MakerBit Pins",
     "url": "/pkg/1010Technologies/pxt-makerbit-pins",
     "cardType": "package"
-},
-{
+}, {
+    "name": "Elecfreaks Wukon",
+    "url": "/pkg/elecfreaks/pxt-wukong",
+    "cardType": "package"
+}, {
    "name": "Pi Supply tinker:kit",
    "url": "/pkg/PiSupply/pxt-tinker-kit",
    "cardType": "package"