Hi deadheadHS​,

There is no official cert guide available from VMware at the moment.

However, the following books can be useful to prepare for VCAP6 track:

• VCAP5-DCD Official Cert Guide (with DVD): VMware Certified Advanced Professional 5 - Data Center Des...
• VCAP5-DCA Official Cert Guide: VMware Certified Advanced Professional 5- Data Center Administration ...
• It Architect: Foundation in the Art of Infrastructure Design: A Practical Guide for It Architects: V...

Also, I would recommend to watch this video - https://app.pluralsight.com/library/courses/designing-vmware-infrastructure/table-of-contents​.

Hope it all helps.