chore: Add preprocessor to test how to use external modules

Author: javierbrea

markdown-confluence-sync.config.js

@@ -0,0 +1,8 @@
+module.exports = {
+  preprocessor: (content) => {
+    // eslint-disable-next-line no-console
+    console.log(content);
+    return content;
+  },
+  logLevel: "debug",
+};