docs(readme): add lighthouse-keeper to integrations (#7399)

readme.md

@@ -282,6 +282,8 @@ This section details services that have integrated Lighthouse data. If you're wo
 
 * **[HTTPArchive](http://httparchive.org/)** - HTTPArchive tracks how the web is built by crawling 500k pages with Web Page Test, including Lighthouse results, and stores the information in BigQuery where it is [publicly available](https://discuss.httparchive.org/t/quickstart-guide-to-exploring-the-http-archive/682).
 
+* **[Lighthouse Keeper](https://lighthouse-keeper.com/)** - Lighthouse Keeper monitors your pages' Lighthouse scores and notifies you if they drop below your thresholds. Lighthouse Keeper is a free service that monitors up to 3 URLs once per day.
+
 * **[SpeedCurve](https://speedcurve.com)** — SpeedCurve is a tool for continuously monitoring web performance across different browsers, devices, and regions. It can aggregate any metric including Lighthouse scores across multiple pages and sites, and allows you to set performance budgets with Slack or email alerts. SpeedCurve is a paid product with a free 30-day trial.
 
 * **[Speedrank](https://speedrank.app)** - Speedrank monitors the performance of your website in the background. It displays Lighthouse reports over time and delivers recommendations for improvement. Speedrank is a paid product with 14-day-trial.