infra/rdv1mc: add user guide for rd-v1-mc platform

Add the initial user guide for the RD-V1-MC platform software stack. The
user guide points to documents that provide information about obtaining
the platform software stack and using the various features it supports.
A table to list the release tags is included as well.

Signed-off-by: Aditya Angadi <aditya.angadi@arm.com>
Change-Id: Ie9543631e29bb8bbc150a1a482ea672a18320bdb