SF patch #1227568, bug #1219273, Expression AST node not documented. Backport...

SF patch #1227568, bug #1219273, Expression AST node not documented.  Backport candidate if anyone cares.

Doc/lib/asttable.tex

@@ -89,6 +89,8 @@
 \lineiii{Ellipsis}{}{}
 \hline 
 
+\lineiii{Expression}{\member{node}}{}
+
 \lineiii{Exec}{\member{expr}}{}
 \lineiii{}{\member{locals}}{}
 \lineiii{}{\member{globals}}{}