Add Web Summit to adopters list
Web Summit is a proud adopter of Linkerd for all our Kubernetes clusters we use to run conferences. Also in use for the [Summit Engine](https://summitengine.com) platform that will run CES 2022 in January.
- [Tradeshift](https://tradeshift.com/)
- [Transit](https://transit.app)
- [Vernacular.ai](https://vernacular.ai/)
+- [Web Summit](https://websummit.com)
- [xCloud](https://www.xbox.com/en-US/xbox-game-streaming/project-xcloud)
- [YouMail](https://www.youmail.com)
- [Zimpler](https://www.zimpler.com/)
