Add note about dropping latex 2.09 compatibility.
diff --git a/Doc/README b/Doc/README
index 2bcd92e..323a113 100644
--- a/Doc/README
+++ b/Doc/README
@@ -2,6 +2,7 @@
 -------------------------------------
 
 This directory contains the Latex sources to the Python documentation.
+They now require latex2e (latex 2.09 compatibility is dropped).
 
 The Python Reference Manual is no longer maintained in Latex.  It is
 now a FrameMaker document.  The FrameMaker 5.0 files (ref.book,