add link to dates.jamstack-oslo.no

Closes: #1 (add `dates.jamstack-oslo.no` page)

README.md

@@ -5,6 +5,7 @@ show the last tuesdays
 [![oclif](https://img.shields.io/badge/cli-oclif-brightgreen.svg)](https://oclif.io)
 [![Version](https://img.shields.io/npm/v/@jamstack-oslo/last-tuesday-in.svg)](https://npmjs.org/package/@jamstack-oslo/last-tuesday-in)
 
+While not exactly the same code running, this site is also showing the dates https://dates.jamstack-oslo.no
 
 ## Installation