Remove details of running in EMIS

docs/data-sources/emis.md

@@ -4,9 +4,5 @@
 
 ## OpenSAFELY-EMIS database builds
 
-At present, EMIS support is enabled for some, but not all, users.
-This is because not all study definitions can run against the EMIS backend.
-There is a [document with more explanation about running studies in EMIS](https://docs.google.com/document/d/1KeToM9gjIKDSyNh_H4M6TWU_xv5yHrkko2bwgOrFsac/edit) (internal only).
-
 When EMIS receive data from external data sources (eg ONS), records are appended to the
 relevant tables, not updated.  The relevant tables have an `upload_date` column, and to get the latest data, we have to query for on `upload_date`.