Add aai/search-data-service as submodule to docs

First AAI doc submodule repo inclusion, following instructions from
readthedocs.io Setting Up page.

Change-Id: I61fe98666370691d447c658262a299bf909d5ae1
Issue-Id: DOC-77
Signed-off-by: MatthewHarffy <Matthew.harffy@amdocs.com>
diff --git a/docs/index.rst b/docs/index.rst
index 4d7eda0..e1e2ab2 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -8,7 +8,7 @@
 .. toctree::
    :maxdepth: 2
 
-   releases/index
+   release/index
    guides/onap-developer/index
    guides/onap-user/index