Steps

1. Create an api-extractor.json file at the root of the package with the following content

   {
     "$schema": "https://developer.microsoft.com/json-schemas/api-extractor/v7/api-extractor.schema.json",
     "extends": "@xwiki/platform-tool-apiextractorconfig/api-extractor.json"
   }

2. Create an etc directory at the root of the package mkdir -p ./etc
3. Add the api-extractor scripts in package.json

   {
     "scripts": {
       "api-extractor:ci": "api-extractor run",
       "api-extractor:local": "api-extractor run --local",
     }
   }

4. Add the dev dependencies with pnpm pnpm add -D @microsoft/api-extractor @xwiki/platform-tool-apiextractorconfig