Information about SQL clusters is missing in SPDocKit's documentation. If your farm databases are using any high-availability solutions like database mirroring or AlwaysOn groups, SPDocKit will not include those details in the documentation. Only the SQL Server where the primary database is located will be shown by SPDocKit.
Application Version: 3.0.0 and newer
There is no workaround for this issue.
Status: Solved in version 7.3