SQL formatting in UPGRADE.

UPGRADE.rst

@@ -113,11 +113,15 @@ back to v1.25.0 you need to:
 
    For PostgreSQL run:
 
+   .. code:: sql
+
       TRUNCATE event_auth_chain_links;
       TRUNCATE event_auth_chains;
 
    For SQLite run:
 
+   .. code:: sql
+
       DELETE FROM event_auth_chain_links;
       DELETE FROM event_auth_chains;