docs: Update README.md

Author: trimox

README.md

@@ -39,7 +39,7 @@ Check out our [Getting Started guide](https://github.com/trimox/angular-mdc-web/
 | button | Available | [View Demo](https://trimox.github.io/angular-mdc-web/#/button-demo) |
 | card | Available | [View Demo](https://trimox.github.io/angular-mdc-web/#/card-demo) |
 | checkbox | Available | [View Demo](https://trimox.github.io/angular-mdc-web/#/checkbox-demo) |
-| dialog | WIP ||
+| dialog | Available | [View Demo](https://trimox.github.io/angular-mdc-web/#/dialog-demo) |
 | drawer | Available | [View Demo](https://trimox.github.io/angular-mdc-web/#/drawer-demo) |
 | elevation | Available | [View Demo](https://trimox.github.io/angular-mdc-web/#/elevation-demo) |
 | fab | Available | [View Demo](https://trimox.github.io/angular-mdc-web/#/fab-demo) |