document %history usage with all lines of a session

Author: pierre-haessig

IPython/core/magics/history.py

@@ -121,10 +121,10 @@ def history(self, parameter_s = ''):
             Line 4, current session
         ``4-6``
             Lines 4-6, current session
+        ``~2/``
+            All lines of session 2 before current
         ``243/1-5``
             Lines 1-5, session 243
-        ``~2/7``
-            Line 7, session 2 before current
         ``~8/1-~6/5``
             From the first line of 8 sessions ago, to the fifth line of 6
             sessions ago.