We strongly suggest engaging our professional services team for any upgrade as there are many caveats to an upgrade, depending on your current configuration.
Version 8.0.6 is backwards compatible with the 8.0.5 client software, however we strongly suggest that all components be upgraded to the latest version at the same time. Please refer to the Release Notes for any compatibility issues: Enterprise Single Sign-On - Release Notes and Guides
With version 8.0.6 there are additional schema changes, but this won't overwrite the existing schema or break anything for the 8.0.5 clients. They will function as normal.
There is no upgrade material available other than what may be included in the documentation with the latest version.