Update demo link in README.md

Author: captainbrosset

temperature-converter/README.md

@@ -1,6 +1,6 @@
 # Temperature converter
 
-➡️ **[Open the demo](https://microsoftedge.github.io/Demos/pwa-getting-started/)** ⬅️
+➡️ **[Open the demo](https://microsoftedge.github.io/Demos/temperature-converter/)** ⬅️
 
 A demo Progressive Web App (PWA) that converts temperatures.  To start learning to use and develop PWAs, start with this sample.