Add initial virtual data idea stub to README

README.md

@@ -50,6 +50,10 @@ NOTE: Add some information about services.
 
 We aim to provide transparent federation. Not only for data queries but also services.
 
+One possible way of achieving this is by using virtual data.
+Operations can be applied to this data by encoding them into the models.
+The data itself is never ingested into the KG.
+
 #### Orchestration
 
 A query which requires data from two sources: