Update SIEM-at-Home README.md

Update SIEM-at-Home `README.md` - Add link to blog 4 Beats on Windows

Author: rwaight

Security Analytics/SIEM-at-Home/README.md

@@ -3,7 +3,8 @@ Monitoring your servers and workstations doesn't have to be difficult or expensi
 1. [Getting started](https://www.elastic.co/blog/elastic-siem-for-small-business-and-home-1-getting-started)
 2. [Securing cluster access](https://www.elastic.co/blog/elastic-siem-for-small-business-and-home-2-securing-cluster-access)
 3. [GeoIP data and Beats config review](https://www.elastic.co/blog/elastic-siem-for-small-business-and-home-3-geoip-data-and-beats-config-review)
-4. Beats on Windows _(coming soon)_
+4. [Beats on Windows](https://www.elastic.co/blog/elastic-siem-for-small-business-and-home-4-beats-on-windows)
+
 
 ## `beats-configs`
 Example configurations for beats when deploying an Elastic SIEM at Home running on Elasticsearch Service