Tweak docs example

docs/getting_started/client.md

@@ -25,7 +25,7 @@ By default, the client will query all OPTIMADE API URLs that it can find via the
     ```python
     from optimade.client import OptimadeClient
     client = OptimadeClient()
-    client.get()
+    results = client.get()
     ```
 
 We can refine the search by manually specifying some URLs: