chore: add debug step to CI workflow for listing documentation files. This update introduces a new job step to list the contents of the mc/site/docs directory, aiding in troubleshooting and ensuring the documentation structure is as expected.

Author: kaihiroi

.github/workflows/ci.yml

@@ -62,3 +62,6 @@ jobs:
         with:
           name: prebuilt_index.jsonl.gz
           path: artifacts/prebuilt_index.jsonl.gz
+
+      - name: Debug List mc/site/docs
+        run: ls -lR mc/site/docs || ls -lR mc/