Add jumalauta/jml-engine-demos to demo sources

Signed-off-by: Mika Rautio <1129758+mrautio@users.noreply.github.com>

Author: mrautio

collections/demo-sources/index.md

@@ -32,6 +32,7 @@ items:
  - in4k/crawlspace
  - monadgroup/sy17
  - monadgroup/re19
+ - jumalauta/jml-engine-demos
 
 display_name: Demo sources
 ---