edit readme

llama_hub/macrometa_gdn/README.md

@@ -1,3 +1,17 @@
 # Macrometa GDN Loader
 
-This loader takes in a Macrometa GDN 
+This loader takes in a Macrometa federation URL, API key, and collection name and returns a list of vectors. 
+
+## Usage
+
+To use this loader, you need to pass the URL and API key through the class contructor, and then load the data using an array of collection names.
+
+```python
+from llama_index import download_loader
+
+MacrometaGDNLoader = download_loader('MacrometaGDNLoader')
+
+collections = ['test_collection']
+loader = MacrometaGDNLoader(url="https://api-macrometa.io",apikey="test")
+vectors= loader.load_data(collection_list=collections)
+```