Add rnib functionality
- The *_pb2.py files were added that compiled by protoc
- `get_list_gnb_ids`, `get_list_enb_ids` added to the _BaseXapp
- rnib repo added as a submodule

Issue-ID: RIC-788

Signed-off-by: yc999.jang <yc999.jang@samsung.com>
Change-Id: Id5c3392592422597b939fccda902c04369566e9e
diff --git a/docs/index.rst b/docs/index.rst
index a3e3f27..74bc561 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -15,6 +15,7 @@
    user-guide.rst
    rmr_api.rst
    alarm_api.rst
+   rnib.rst
    developer-guide.rst
    release-notes.rst