WIP: Upgrading from 0.4.0 to 0.5.0

docs/upgrading.md

@@ -10,6 +10,15 @@ To find the differences (requires [python yq package](https://pypi.org/project/y
     yq -y -rS . ansible/group_vars/all/settings.yml.example > /tmp/upstream.yml
     diff /tmp/mine.yml /tmp/upstream.yml
 
+Before you upgrade please look at the `CHANGELOG.md` file to review what changed
+between the versions.
+
+## Upgrading from 0.4.0 to 0.5.0
+
+Unfortunatly we can't ensure a smooth upgrade for this version neither.
+Please read the section below on how to do an upgrade by installing a the new
+OAS version from scratch after backing up your data.
+
 ## Upgrading from 0.3.0 to 0.4.0
 
 There is no easy upgrade path from version 0.3.0 to version 0.4.0. As far as we