obsolete paragraph in automake.texi

[Stepan Kasal]

Hello,
  the node `true' of automake.texi explains, among other issues,
how should be explicite rules hand-crafted in order to interact
nicely with ansi2knr option.  The explanation mentions files
        true._c, true._o and false._o
I beleive that current implementation uses *_.c and *_.o instead,
thus the above must obsolete.

I don't have enough knowledge to prepare a patch.

Have a nice day,
        Stepan Kasal