Merge pull request plotly#274 from plotly/dash-datashader

Dash-datashader add demo app link

Author: YunkeXiao

apps/dash-datashader/README.md

@@ -3,6 +3,9 @@
 This is a demo of the [Dash](https://plot.ly/products/dash/) interactive Python framework developed by [Plotly](https://plot.ly/).
 Dash abstracts away all of the technologies and protocols required to build an interactive web-based application and is a simple and effective way to bind a user interface around your Python code.
 
+Try out the [demo app here](https://dash-gallery.plotly.host/dash-datashader/).
+
+
 To learn more check out our [documentation](https://dash.plot.ly).
 
 ### Contributing