The documentation was updated to stress that the name of the
variable to be set must be specified without the ${} syntactic
sugar. Also the TODO was updated to stress we don't have yet
examples of usage where doing the TODO would bring a benefit.
Change-Id: I614769c9c2565c0463633d56b306510c829e3965 Signed-off-by: Jozef Behran <jbehran@cisco.com>