Docs: Update RSS readme

- Add instructions about loading provisioning bundles.
- Remove imgtool boot-record parameter as it is not required with
  with RSS measured boot.
- Correct image load address offset.

Signed-off-by: Jamie Fox <jamie.fox@arm.com>
Change-Id: I26fb31d218008fb6811e09f136ee56820ba67ba5
1 file changed