docs/aemfvp-a: Minor updates in user guide for aemfvp-a

Modify the GRUB link and add "iasl" as a required package in the
user-guide.rst. Add the tag version as the release name in the
change-log.rst.

Signed-off-by: Selvarasu Ganesan <selvarasu.ganesan@arm.com>
Change-Id: I64f51e920deb5dea25c5fc212b25f7466f806cf7