docs(README): Fix doctest

Author: tony

README.md

@@ -92,8 +92,10 @@ Session($1 foo)
 Control your session:
 
 ```python
-# Assign session to `session`:
+>>> server.sessions[0].rename_session('foo')
+Session($1 foo)
 >>> session = server.find_where({ "session_name": "foo" })
+Session($1 foo)
 >>> session.new_window(attach=False, window_name="ha in the bg")
 Window(@8 2:ha in the bg, Session($3 foo))
 >>> session.kill_window("ha in")