Added exercise entry in track config.json.

Author: BethanyG

config.json

@@ -34,6 +34,14 @@
         "prerequisites": ["basics"],
         "status": "wip"
       },
+      {
+        "slug": "meltdown-mitigation",
+        "name": "Meltdown Mitigation",
+        "uuid": "50c88b36-e2e2-46e5-b6c4-bb7e714c375a",
+        "concepts": ["conditionals"],
+        "prerequisites": ["basics", "booleans", "comparisons"],
+        "status": "wip"
+      },
       {
         "slug": "tisbury-treasure-hunt",
         "name": "Tisbury Treasure Hunt",