Issue 431 docs multiple feature stores (#477)

* Extending docs, see issue 431

* fix formatting issues

docs/advanced-functionality.rst

@@ -145,6 +145,19 @@ And of course you can delete a featureset::
 
     DELETE _ltr/wikipedia/_featureset/attempt_1
 
+You can use featuresets of specific feature stores by using the :code:`store` parameter in the :code:`sltr` part of your query when logging features::
+
+    "sltr": {
+        "_name": "logged_featureset",
+        "featureset": "attempt_1",
+        "store": "wikipedia",
+        "params": {
+            "keywords": "star"
+        }
+    }
+
+In case no :code:`store` is specified the default store will be used for looking up the featureset.
+
 =============================
 Model Caching
 =============================