add links for externalapi/nbi
Issue-ID: DOC-256

Change-Id: I4e236eca2cf78424ccfd40dd90a5eaf76dadc75f
Signed-off-by: Rene Robert <rene.robert@orange.com>
diff --git a/docs/guides/onap-developer/architecture/references.rst b/docs/guides/onap-developer/architecture/references.rst
index 6a72a39..49eb3c5 100644
--- a/docs/guides/onap-developer/architecture/references.rst
+++ b/docs/guides/onap-developer/architecture/references.rst
@@ -45,6 +45,7 @@
    Holmes <../../../submodules/holmes/rule-management.git/docs/platform/architecture.rst>
    SDN Controller OAM <../../../submodules/sdnc/oam.git/docs/architecture.rst>
    ../../../submodules/so.git/docs/architecture.rst
+   NBI - NorthBound API <../../../submodules/externalapi/nbi.git/docs/architecture/architecture.rst>
 
 Common Services
 ---------------
@@ -76,7 +77,7 @@
    :titlesonly:
 
 
- 
+
 Other
 -----