added example of sites.json to readme

README.md

@@ -23,6 +23,18 @@ Start database
 docker-compose up
 ```
 
+Example `sites.json`
+```json
+[
+    {
+        "name": "Example Site Name",
+        "ingredient_class": "example-ingredients-item-name",
+        "name_class" : "example-heading-content",
+        "base_url" : "https://www.example.com/recipe/"
+    }
+]
+```
+
 Initialize database and recipe sites
 ```sh
 python src/db.py