Update web app link in the README (#333)

README.md

@@ -33,7 +33,7 @@ What is Speckle? Check our ![YouTube Video Views](https://img.shields.io/youtube
 
 Give Speckle a try in no time by:
 
-- [![speckle XYZ](https://img.shields.io/badge/https://-speckle.xyz-0069ff?style=flat-square&logo=hackthebox&logoColor=white)](https://speckle.xyz) ⇒ creating an account at our public server
+- [![speckle](https://img.shields.io/badge/https://-app.speckle.systems-0069ff?style=flat-square&logo=hackthebox&logoColor=white)](https://app.speckle.systems) ⇒ creating an account at our public server
 - [![create a droplet](https://img.shields.io/badge/Create%20a%20Droplet-0069ff?style=flat-square&logo=digitalocean&logoColor=white)](https://marketplace.digitalocean.com/apps/speckle-server?refcode=947a2b5d7dc1) ⇒ deploying an instance in 1 click
 
 ### Resources