CMake buildsystem design document

Change-Id: I9b69f2731b0d43ead4cacfa9844c6137c57f5aec
Signed-off-by: Balint Dobszay <balint.dobszay@arm.com>
diff --git a/docs/index.rst b/docs/index.rst
index 5088bfd..7413edd 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -14,6 +14,7 @@
    plat/index
    perf/index
    security_advisories/index
+   design_documents/index
    change-log
    change-log-upcoming
    glossary
@@ -82,7 +83,7 @@
 
 --------------
 
-*Copyright (c) 2013-2019, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2013-2020, Arm Limited and Contributors. All rights reserved.*
 
 .. _Armv7-A and Armv8-A: https://developer.arm.com/products/architecture/a-profile
 .. _Secure Monitor: http://www.arm.com/products/processors/technologies/trustzone/tee-smc.php