Remove received_recent_date docs until deployed

Author: Jennie Lees

README.md

@@ -109,10 +109,6 @@ for thread in namespace.threads.where(starred=True):
 # List all threads with '[email protected]'
 for thread in namespace.threads.where(any_email='[email protected]').items():
     print thread.subject
-
-# List threads in order of most recently received message (excludes sent messages)
-for thread in namespace.threads.where(sort='received_recent_date'):
-    print thread.subject
 ```