action: publish documentation when VERSION is changed

When VERSION is changed, do not wait for daily cron and publish
documentation immediately to keep things in sync.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

.github/workflows/doc-publish.yml

@@ -8,6 +8,8 @@ on:
   schedule:
     - cron:  '50 22 * * *'
   push:
+    paths:
+      - 'VERSION'
     tags:
       # only publish v* tags, do not care about zephyr-v* which point to the
       # same commit