Merge pull request #282 from alphagov/readme-analytics

docs: link to analytics dashboard from README

Author: aaronfowles

README.md

@@ -186,3 +186,7 @@ log.error(error, 'error')
 // If you want to log an object:
 log.info({ a: 123, b: 456 }, 'This is a log')
 ```
+
+# Web analytics
+
+Some of the activity of users who consent to a tracking cookie can be viewed in a [GA4 dashboard](https://analytics.google.com/analytics/web/?authuser=0#/p303522524/reports/intelligenthome).