[O] Bug: link to gnuplot [9.1.14 (9.1.14-1-g4931fc-elpa @ /home/kiwibird/.emacs.d/elpa/org-9.1.14/)]

[Kevin Brubeck Unhammer]

When I do

    C-c " g 

or

    M-x org-plot/gnuplot

I get

    org-plot/gnuplot: Cannot open load file: No such file or directory, gnuplot

It'd be nice if org-plot/gnuplot could instead `message' me a link to
the package that needs installing (or at least if the docstring for that
function could mention it).

Also, the link from Worg is wrong,
https://orgmode.org/worg/org-tutorials/org-plot.html points to
http://cars9.uchicago.edu/~ravel/software/gnuplot-mode.html instead of
http://xafs.org/BruceRavel/GnuplotMode or
https://github.com/bruceravel/gnuplot-mode/

(This is especially annoying since Bruce Ravel's gnuplot isn't in GNU
ELPA, while Melpa confusingly has both gnuplot and gnuplot-mode.)

Emacs  : GNU Emacs 26.1 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
 of 2018-05-29
Package: Org mode version 9.1.14 (9.1.14-1-g4931fc-elpa @ 
/home/kiwibird/.emacs.d/elpa/org-9.1.14/)