Update collection.json after org swap

Author: jonhealy1

Diff for: examples/collection.json

@@ -1,7 +1,7 @@
 {
   "stac_version": "1.1.0",
   "stac_extensions": [
-    "https://healy-hyperspatial.github.io/merkle-tree/v1.0.0-beta.2/schema.json"
+    "https://stacchain.github.io/merkle-tree/v1.0.0-beta.2/schema.json"
   ],
   "type": "Collection",
   "id": "collection-123",
@@ -60,4 +60,4 @@
       "rel": "item"
     }
   ]
-}
+}