Use JupyterLite for the R demo (#801)

Author: jtpio

try.html

@@ -79,8 +79,8 @@
     - title: R
       description: How to use Jupyter with R
       src: try/R.svg
-      alt: R logo - Launch R demo Binder
-      url: https://mybinder.org/v2/gh/binder-examples/r/HEAD?filepath=index.ipynb
+      alt: R logo - Launch R demo
+      url: https://jupyter.org/try-jupyter/lab/index.html?path=notebooks%2Fr.ipynb
 
     - title: Ruby
       description: How to use Jupyter with Ruby