doc: one of the fixes for an ambiguous grammar was ambiguous too

Reported by Аскар Сафин.
http://lists.gnu.org/archive/html/bug-bison/2012-11/msg00024.html

* doc/bison.texi (Reduce/Reduce): Fix the resulting ambiguity using
precedence/associativity directives.

THANKS

@@ -1,8 +1,9 @@
 Bison was originally written by Robert Corbett.  It would not be what
 it is today without the invaluable help of these people:
 
+Аскар Сафин              [email protected]
 Airy Andre                [email protected]
-Akim Demaille             akim@freefriends.org
+Akim Demaille             akim@lrde.epita.fr
 Albert Chin-A-Young       [email protected]
 Alexander Belopolsky      [email protected]
 Alexandre Duret-Lutz      [email protected]