Drop Product Guide

Product Guide was not built for oVirt as marked relevant for RHV only.
Dropping as it's unused.

Signed-off-by: Sandro Bonazzola <sandro.bonazzola@gmail.com>

Author: sandrobonazzola

_config.yml

@@ -163,7 +163,6 @@ exclude:
   - documentation/virtual_machine_management_guide/assembly*
   - documentation/doc-Technical_Reference/**
   - documentation/doc-Release_Notes/**
-  - documentation/doc-Product_Guide/**
   - documentation/doc-Python_SDK_Guide/topics
   - documentation/doc-Python_SDK_Guide/chap*
   - documentation/doc-Planning_and_Prerequisites_Guide/topics