Add version added info for with statement and context managers
diff --git a/Doc/ref/ref7.tex b/Doc/ref/ref7.tex
index a5a6eaf..ecbc756 100644
--- a/Doc/ref/ref7.tex
+++ b/Doc/ref/ref7.tex
@@ -312,6 +312,8 @@
 \section{The \keyword{with} statement\label{with}}
 \stindex{with}
 
+\versionadded{2.5}
+
 The \keyword{with} statement is used to wrap the execution of a block
 with methods defined by a context manager (see
 section~\ref{context-managers}). This allows common