[gimp-web] themes: add nightly link for macOS builds.

[Jehan <jehanp src gnome org>]

commit f67db52b5d61a3f452c834775a8e77f79538a69c
Author: Jehan <jehan girinstud io>
Date:   Sat Jul 9 13:51:14 2022 +0200

    themes: add nightly link for macOS builds.
    
    Thanks to lukaso work!

 .../newgimp/templates/downloads-development.html   | 34 +++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)
---
diff --git a/themes/newgimp/templates/downloads-development.html 
b/themes/newgimp/templates/downloads-development.html
index 636dfc59..2e53df23 100644
--- a/themes/newgimp/templates/downloads-development.html
+++ b/themes/newgimp/templates/downloads-development.html
@@ -263,6 +263,38 @@
           <a href="https://www.virustotal.com/#/file/{{ MACOS_HASH_DEVELOPMENT }}/detection">{{ 
MACOS_FILE_DEVELOPMENT }}</a>
         </p>
 
+      {% if GIMP_VERSION_NIGHTLY is defined %}
+      <h3>Automatic development builds</h3>
+      <p>
+          Automatic builds (sometimes called "nightlies") are generated at
+          regular intervals by our Continuous Integration process. This
+          allows to run the last version of our code, though it also means
+          you will get possibly very unstable work-in-progress, just as it
+          is made. Therefore ⚠️  <strong>be aware that you would be running
+          very experimental code!</strong> ⚠️
+          These builds are meant to test future GIMP versions and help us
+          debug, we do not advise to use these for production.
+      </p>
+      <ol>
+        <li>Go to GIMP's <a
+        
href="https://app.circleci.com/pipelines/github/GNOME/gimp-macos-build?branch=master&filter=all";>scheduled
+        pipelines listing</a> and click the latest "<strong>Success</strong>"
+        button listed at the top of the list.</li>
+        <li>Click the job <pre>build-gimp-2-99-and-package</pre> in the right end</li>
+        <li>Click the "Artifacts" tab</li>
+        <li>Finally click the <pre>builds/gimp-{{GIMP_VERSION_NIGHTLY}}-*-master.dmg</pre>
+        file to download and install the GIMP nightly.</li>
+      </ol>
+      <dl>
+        <dt>Note<dt>
+        <dd><em>
+          Additionally to the code being experimental, these automated
+          installers themselves are an experimental convenience and may
+          still have various issues. In particular, they are not humanly
+          tested, unlike released versions.
+        </em></dd>
+      </dl>
+      {% endif %}
 
         <h3>Older Downloads</h3>
         <p>Previous installers for macOS/OSX can be found here: <a 
href='//download.gimp.org/mirror/pub/gimp/v2.9/osx/'>download.gimp.org</a>.</p>
@@ -373,7 +405,7 @@
       <li>Navigate to the <pre>build/windows/installer/_Output/</pre>
       directory</li>
       <li>Finally click the <pre>gimp-{{ GIMP_VERSION_NIGHTLY }}-setup.exe</pre>
-      file to download and install it.</li>
+      file to download and install the GIMP nightly.</li>
     </ol>
     <!--
     This link should ideally send to the last nightly installer, but it