Tail recursion no longer supported by "function".

--- a/src/Doc/Functions/document/intro.tex	Thu Jul 03 14:40:36 2014 +0200
+++ b/src/Doc/Functions/document/intro.tex	Thu Jul 03 16:42:15 2014 +0200
@@ -50,6 +50,8 @@
 a few of technical issues around \cmd{recdef}, and allow definitions
 which were not previously possible.
 
+In addition there is also the \cmd{partial\_function} command
+(see \cite{isabelle-isar-ref}) that supports the definition of partial
+and tail recursive functions.
 
 
-