bug#58196: Trivial update to ediprolog

[Stefan Kangas]

Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs@gnu.org> writes:

>>   3) The image in line 101 of README.md is not shown.
>
> I think it's the same problem that the relative link to `factorial.png`
> fails.  The case is a bit different in the sense that I can't argue this
> time that the link is redundant anyway :-)
>
> Maybe we could try and recognize those links and redirect them to something 
> like
> https://git.savannah.gnu.org/cgit/emacs/elpa.git/plain/factorial.png?h=externals/ediprolog
> but going through `cgit` is rather inefficient (and recognizing those
> links reliably is not completely trivial either).

We could just copy any image files to the web directory, and add some
heuristics to change any <img>-tags in the HTML (exported from
markdown2, org-mode, etc.) to point there.

For example, we could put factorial.png in
/images/<package-name>/factorial.png.  The only cost is a bit of
diskspace, but it shouldn't be a lot as there is already some incentive
to keep down file sizes.