docs(readme): add Apdex to integrations (#11655)

readme.md

@@ -339,6 +339,8 @@ This section details services that have integrated Lighthouse data. If you're wo
 
 * **[Foo](https://www.foo.software/lighthouse)** - Lighthouse-as-a-service offering free and premium plans. Provides monitoring and historical reporting of Lighthouse audits with CircleCI, GitHub, and other integrations. Features include Slack notifications, PR comment reporting and more.
 
+* **[Apdex](https://apdex.co)** - Apdex is a website performance service. The main features are historical Lighthouse report visualizations, mobile/desktop options, alerts, uptime monitoring, and more. There are flexible paid plans and a 30-day free trial.
+
 ## Lighthouse Integrations in non-Web Perf services
 
 * **[PageWatch](https://pagewatch.dev/)** — PageWatch is a tool to find problem pages on your website.  It provides insights into spelling errors, layout issues, slow pages (powered by Lighthouse) and more.  PageWatch is offered via free and paid plans.