[R] Trailing on r-help messages

[Gabor Grothendieck]

I would like to propose that we change the trailer on r-help
messages which is currently:

   R-help at stat.math.ethz.ch mailing list
   https://stat.ethz.ch/mailman/listinfo/r-help
   PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

to add the following 4th line:

   and provide minimal, self-contained, reproducible code.

The posting guide is so long that I suspect few people really read
it so at least this way the most important part of the message about
posting would be readily visible without further user action.

Of course minimal refers to cutting the code down to remove
anything not related to the question at hand while self-contained
and reproducible refer to being able to copy the code from
the post and paste it into an R session to reproduce the
problem.