No macro for 'micro-chat` card desc (#1470)

Author: ganicke

docs/tutorials.md

@@ -40,7 +40,7 @@ Here are some cool tutorials to get you started with your @boardname@!
 }, {
   "name": "Micro Chat",
   "url":"/projects/micro-chat",
-  "description": "Build your own social network made of @boardnames.",
+  "description": "Build your own social network made of micro:bits.",
   "imageUrl": "/static/mb/projects/a9-radio.png",
   "cardType": "tutorial"
 }]