Possible bug in man page

[Joachim Nilsson]

Hi Marc,

I think I've find a minor typo in an example in the documentation.
In the Examples section of ev_periodic the callback is:

   clock_cb (struct ev_loop *loop, ev_io *w, int revents)

but I think it should be:

   clock_cb (struct ev_loop *loop, ev_periodic *w, int revents)

Regards
 /Joachim