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>
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 2735f17..0e3b2fc 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -1132,6 +1132,13 @@
   means platform hook won't be checked and CMOs will always be performed when
   related functions are called.
 
+- ``ERRATA_ABI_SUPPORT``: Boolean option to enable support for Errata management
+  firmware interface for the BL31 image. By default its disabled (``0``).
+
+- ``ERRATA_NON_ARM_INTERCONNECT``: Boolean option to enable support for the
+  errata mitigation for platforms with a non-arm interconnect using the errata
+  ABI. By default its disabled (``0``).
+
 GICv3 driver options
 --------------------