ditaa --svg option is missing when building doc/src/sgml/images

Hi,

I am working on writing a meson.build file for doc/src/sgml/images,
but I ran into an issue when Meson tries to invoke `ditaa`:

/usr/bin/ditaa -E -S --svg
../../postgres/doc/src/sgml/images/temporal-references.txt
doc/src/sgml/images/temporal-references.txt.svg.tmp
Unrecognized option: --svg
usage: ditaa <INPFILE> [OUTFILE] [-A] [-b <BACKGROUND>] [-d] [-E] [-e
<ENCODING>] [-h] [--help] [-o] [-r] [-S] [-s <SCALE>] [-T] [-t
<TABS>] [-v] [-W]

This issue also happens on autoconf builds:

$ rm doc/src/sgml/images/pagelayout.svg && make all -C doc/src/sgml/images/
ditaa -E -S --svg pagelayout.txt pagelayout.svg.tmp
Unrecognized option: --svg
usage: ditaa <INPFILE> [OUTFILE] [-A] [-b <BACKGROUND>] [-d] [-E] [-e
<ENCODING>] [-h] [--help] [-o] [-r] [-S] [-s <SCALE>] [-T] [-t
<TABS>] [-v] [-W]

It appears that the --svg option was introduced in ditaa v0.11.0 [1],
while Debian ships ditaa v0.10.x [2], which does not support this
option.

Additionally, doc/src/sgml/images/README mentions: Ditaa
(http://ditaa.sourceforge.net/) but this website has an even older
version, v0.9.*.

If I am not missing anything, what do you think about updating this
URL with the github URL [3]?

[1] https://github.com/stathissideris/ditaa
[2] https://packages.debian.org/sid/ditaa
[3]
diff --git a/doc/src/sgml/images/README b/doc/src/sgml/images/README
index 07c45802553..60fcea29980 100644
--- a/doc/src/sgml/images/README
+++ b/doc/src/sgml/images/README
@@ -13,7 +13,7 @@ involve diffable source files.
These tools are acceptable:

- Graphviz (https://graphviz.org/)
-- Ditaa (http://ditaa.sourceforge.net/)
+- Ditaa (https://github.com/stathissideris/ditaa)

--
Regards,
Nazir Bilal Yavuz
Microsoft