Added Webstudio.is (#398)

Author: 360Creators

README.md

@@ -85,6 +85,7 @@ As vendors adopt the specification and new requirements appear, the community gr
 - [Toolabs](https://www.toolabs.com)
 - [Tokens Studio](https://www.tokens.studio)
 - [Universal Design Tokens](https://github.com/universal-design-tokens/udt)
+- [Webstudio](https://webstudio.is)
 - [Zendesk](https://www.zendesk.com)
 - [Zeplin](https://zeplin.io)
 - [zeroheight](https://www.zeroheight.com)