Fix promo image, icon etc (#1235)

Completes #1234

Author: recrwplay

publish.yml

@@ -55,7 +55,9 @@ asciidoc:
     neo4j-docs-base-uri: /docs
     # NODES 2025 CFP
     page-ad-overline-link: https://neo4j.com/nodes-2025/
-    page-ad-image: /assets/img/nodes-25.png
+    page-ad-overline: ''
+    page-ad-image: '{neo4j-docs-base-uri}/assets/img/nodes-25.png'
+    page-ad-icon: ''
     page-ad-title: Nov 6 2025
     page-ad-description: The Call for Papers is now open and we want to hear about your graph-related projects. Submit your talks by June 15
     page-ad-link: https://neo4j.com/nodes-2025/