Document the byte_order value in the sys module.
diff --git a/Doc/lib/libsys.tex b/Doc/lib/libsys.tex
index 54f9493..5cc833d 100644
--- a/Doc/lib/libsys.tex
+++ b/Doc/lib/libsys.tex
@@ -20,6 +20,14 @@
\code{argv} has zero length.
\end{datadesc}
+\begin{datadesc}{byte_order}
+ An indicator of the native byte order. This will have the value
+ \code{'big'} on big-endian (most-signigicant byte first) platforms,
+ and \code{'little'} on little-endian (least-significant byte first)
+ platforms.
+ \versionadded{2.0}
+\end{datadesc}
+
\begin{datadesc}{builtin_module_names}
A tuple of strings giving the names of all modules that are compiled
into this Python interpreter. (This information is not available in