scp_v2.11: Release notes for SCP-firmware v2.11

Created by: nicola-mazzucato-arm

With this patch the change log is updated to contain description for new features, improvements and fixes contained in this release.

Please note that some remarks have been added for the newly added tool Unit Test and its implications for the contributors.

Change-Id: Iac4a3bcef51d818dbfa88207d5fb857eeea0c4e7 Signed-off-by: Nicola Mazzucato nicola.mazzucato@arm.com