This patch adds explanations and examples of the makefile targets for hypervisor
configuration, including `hvdefconfig`, `hvshowconfig`, `hvdiffconfig` and
`hvapplydiffconfig`.
Tracked-On: #5644
Signed-off-by: Junjie Mao <junjie.mao@intel.com>
Signed-off-by: David B. Kinder <david.b.kinder@intel.com>