Enable GitHub Wiki for Cloudberry via .asf.yaml

This change udpates .asf.yaml to enable the GitHub Wiki feature for the
Cloudberry project. The Wiki will be used to host informal or
non-website-friendly documentation, such as feature designs, proposals,
and marketing notes, etc.

See: https://lists.apache.org/thread/737t0woh5hm7hswpr4j3xoq2kptk0d98

Author: tuhaihe

.asf.yaml

@@ -54,8 +54,8 @@ github:
 
   # GitHub repository feature toggles
   features:
-    # Disable GitHub wiki as documentation is maintained elsewhere
-    wiki: false
+    # Enable GitHub wiki as documentation is maintained elsewhere
+    wiki: true
     # Enable GitHub Issues for bug tracking and feature requests
     issues: true
     # Enable GitHub Projects for project management and planning