docker/l3d#74 Move all documentation to devops-tools doc

README.md

-ATTENTION: Zammad requires ElasticSearch 5.6.x
+# Zammad
 
-See https://docs.zammad.org/en/latest/install-elasticsearch.html
+You find all the details in the [full documentation](https://devops-tools.docs.lakedrops.com/ansible/roles/zammad/).