docs(errata_abi): document the errata abi changes

Updated errata ABI feature enable flag and the errata non-arm
interconnect based flag, the default values for when the
feature is not enabled.

Change-Id: Ieb2144a1bc38f4ed684fda8280842a18964ba148
Signed-off-by: Sona Mathew <SonaRebecca.Mathew@arm.com>
3 files changed