docs: add getting started section and docs build

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I45e961f52b7af57fe6599bde623fb75093c7cad9
diff --git a/docs/index.rst b/docs/index.rst
index 1971007..11d8cf2 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -6,6 +6,7 @@
    :numbered:
 
    about/index
+   getting_started/index
    design/index
    threat_model_spm
    change-log