Add link to master update site

Signed-off-by: Taylor Smock <taylor.smock@kaart.com>

public/index.html

@@ -8,4 +8,5 @@
 
   <a href="https://gitlab.com/gokaart/JOSM_MapWithAI">Code mirror on GitLab</a>
   <a href="https://gitlab.com/gokaart/JOSM_MapWithAI/pipelines">CI builds (with downloadable artifacts)</a><br>
+  <a href="https://gokaart.gitlab.io/JOSM_MapWithAI/snapshot/master/update-site">Update Site for current state of the master branch</a><br>
 </div>