add externalapi/nbi to doc
Issue-ID: DOC-254

Change-Id: Ic2830edd99bfd97a59c4dcdf753e56fca4b2873d
Signed-off-by: Rene Robert <rene.robert@orange.com>
diff --git a/.gitmodules b/.gitmodules
index 7042def..052f3a1 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -303,3 +303,6 @@
 	url = ../music
 	branch = .
 	ignore = dirty
+[submodule "docs/submodules/externalapi/nbi.git"]
+	path = docs/submodules/externalapi/nbi.git
+	url = ../externalapi/nbi