DOC: update README

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

README.md

@@ -9,9 +9,12 @@ OPENAIR-CN-5G is an implementation of the 3GPP specifications for the 5G Core Ne
 At the moment, it contains the following network elements:
 
 * Access and Mobility Management Function (**AMF**)
+* Authentication Server Management Function (**AUSF**)
+* Network Repository Function (**NRF**)
 * Session Management Function (**SMF**)
+* Unified Data Management (**UDM**)
+* Unified Data Repository (**UDR**)
 * User Plane Function (**UPF**)
-* Network Repository Function (**NRF**)
 
 Each has its own repository: this repository (`oai-cn5g-nrf`) is meant for NRF.