doc: liby's main arms the internationalization

Reported by Nicolas Bedon.
<https://lists.gnu.org/archive/html/bug-bison/2014-11/msg00005.html>

* doc/bison.texi (Yacc Library): Document the call the setlocale.

THANKS

@@ -95,6 +95,7 @@ Mike Sullivan             Mike.sullivan@Oracle.COM
 Neil Booth                NeilB@earthling.net
 Nelson H. F. Beebe        beebe@math.utah.edu
 Nick Bowler               nbowler@elliptictech.com
+Nicolas Bedon             nicolas.bedon@univ-rouen.fr
 Nicolas Burrus            nicolas.burrus@epita.fr
 Nicolas Tisserand         nicolas.tisserand@epita.fr
 Noah Friedman             friedman@gnu.org

doc/bison.texi

@@ -10382,9 +10382,23 @@ declare @code{yyerror} as follows:
 int yyerror (char const *);
 @end example
 
-Bison ignores the @code{int} value returned by this @code{yyerror}.
-If you use the Yacc library's @code{main} function, your
-@code{yyparse} function should have the following type signature:
+@noindent
+The @code{int} value returned by this @code{yyerror} is ignored.
+
+The implementation of Yacc library's @code{main} function is:
+
+@example
+int main (void)
+@{
+  setlocale (LC_ALL, "");
+  return yyparse ();
+@}
+@end example
+
+@noindent
+so if you use it, the internationalization support is enabled (e.g., error
+messages are translated), and your @code{yyparse} function should have the
+following type signature:
 
 @example
 int yyparse (void);