Update branches in wiki-playbook.yml

Author: riccardobl

wiki-playbook.yml

@@ -6,7 +6,7 @@ site:
 content:
   sources:
   - url: https://github.com/jMonkeyEngine/wiki.git
-    branches: [HEAD, v3.4, v3.3, v3.2]
+    branches: [HEAD, v3.8, v3.4, v3.3, v3.2]
     start_path: docs
   - url: https://github.com/jMonkeyEngine/wiki-ui
     branches: HEAD