(main): Add bug report info in --help message.

src/emacs.c

@@ -603,7 +603,9 @@ Usage: %s [-t term] [--terminal term]  [-nw] [--no-windows]  [--batch]\n\
       [-q] [--no-init-file]  [-u user] [--user user]  [--debug-init]\n\
       [--version] [--no-site-file]\n\
       [-f func] [--funcall func]  [-l file] [--load file]  [--insert file]\n\
-      [+linenum] file-to-visit  [--kill]\n", argv[0]);
+      [+linenum] file-to-visit  [--kill]\n\
+Report bugs to bug-gnu-emacs@prep.ai.mit.edu.  First, please see\n\
+the Bugs section of the Emacs manual or the file BUGS.", argv[0]);
       exit (0);
     }