Add handover tutorial

Co-authored-by: rmagueta <rmagueta@allbesmart.pt>

doc/README.md

@@ -53,6 +53,7 @@ There is some general information in the [OpenAirInterface Gitlab Wiki](https://
 - [How to run with E2 agent](../openair2/E2AP/README.md)
 - [How to run the physical simulators](./physical-simulators.md)
 - [How to setup OAI with Nvidia Aerial and Foxconn](./Aerial_FAPI_Split_Tutorial.md)
+- [How to do a handover](./handover-tutorial.md)
 
 Legacy unmaintained files:
 - [`L2NFAPI_NOS1.md`](./L2NFAPI_NOS1.md), [`L2NFAPI_S1.md`](./L2NFAPI_S1.md):

doc/RRC/ho.mmd

+block-beta
+  columns 5
+  space space DU0 space UE
+  CU space space space space
+  space space DU1 space pos["new pos"]
+  CU<-- "F1" -->DU0
+  CU<-- "F1" -->DU1
+  DU0-- "Uu" -->UE
+  UE-- "move" -->pos