ci: fix jq parse error in changed files list step

Pass the changed files JSON through an environment variable instead
of direct interpolation to avoid shell quoting issues.

Signed-off-by: Ramon Roche <mrpollo@gmail.com>

.github/workflows/docs-orchestrator.yml

@@ -224,9 +224,11 @@ jobs:
             docs/en/**/*.md
 
       - name: Save changed files list
+        env:
+          ALL_CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
         run: |
           mkdir -p logs
-          echo '${{ steps.changed-files.outputs.all_changed_files }}' | jq '.' > ./logs/prFiles.json
+          echo "$ALL_CHANGED_FILES" | jq '.' > ./logs/prFiles.json
           echo "Changed files:"
           cat ./logs/prFiles.json