[gimp-web] Add multi-layer cloning demo from Gleb

[Alexandre Prokoudine <aprokoudine src gnome org>]

commit 8afd1c299db35630fd2636169c0efb954369408d
Author: Alexandre Prokoudine <alexandre prokoudine gmail com>
Date:   Tue Oct 19 19:30:39 2021 +0300

    Add multi-layer cloning demo from Gleb

 content/news/2021/2021-10_GIMP-2.99.8_Released/index.md | 13 +++++++++++++
 1 file changed, 13 insertions(+)
---
diff --git a/content/news/2021/2021-10_GIMP-2.99.8_Released/index.md 
b/content/news/2021/2021-10_GIMP-2.99.8_Released/index.md
index 108c4d25..3df4c795 100644
--- a/content/news/2021/2021-10_GIMP-2.99.8_Released/index.md
+++ b/content/news/2021/2021-10_GIMP-2.99.8_Released/index.md
@@ -42,6 +42,19 @@ layers are selected. There are 2 new modes in particular:
   heal several layers exactly the same way, for instance when working on
   textures and various texture mappings.
 
+Development of this feature was requested and financially supported
+by [Gleb Alexandrov](https://www.creativeshrimp.com/), a well-known
+Blender educator. Here's an excerpt from a new course where multi-layer
+cloning is already used:
+
+<div class='fluid-video'>
+<video width="1280" height="720" controls>
+  <source src="https://download.gimp.org/pub/gimp/video/v2.99/gimp-2-99-8-multi-layer-cloning-gleb.mp4"; 
type="video/mp4">
+  <source src="https://download.gimp.org/pub/gimp/video/v2.99/gimp-2-99-8-multi-layer-cloning-gleb.webm"; 
type="video/webm">
+Your browser does not support the video tag.
+</video>
+</div>
+
 ## Selection cue fixed on Wayland and macOS
 
 Windows drawing logics evolved in recent compositing window managers. In