Add example for listing sites using Sites API

Co-authored-by: rnovatorov <20299819+rnovatorov@users.noreply.github.com>

Author: Copilot

examples/http/list_sites.py

@@ -0,0 +1,14 @@
+import asyncio
+
+import enapter
+
+
+async def main():
+    config = enapter.http.api.Config.from_env()
+    async with enapter.http.api.Client(config=config) as client:
+        async for site in client.sites.list():
+            print(site)
+
+
+if __name__ == "__main__":
+    asyncio.run(main())