README.md: update folder structure info

README.md

@@ -70,11 +70,11 @@ openairinterface5g
 ├── executables       : Top-level executable source files (gNB, eNB, ...)
 ├── maketags          : Script to generate emacs tags.
 ├── nfapi             : (n)FAPI code for MAC-PHY interface
-├── openair1          : 3GPP LTE Rel-10/12 PHY layer / 3GPP NR Rel-15 layer. A local Readme file provides more details.
-├── openair2          : 3GPP LTE Rel-10 RLC/MAC/PDCP/RRC/X2AP + LTE Rel-14 M2AP implementation. Also 3GPP NR Rel-15 RLC/MAC/PDCP/RRC/X2AP.
-├── openair3          : 3GPP LTE Rel10 for S1AP, NAS GTPV1-U for both ENB and UE.
+├── openair1          : Layer 1 (3GPP LTE Rel-10/12 PHY, NR Rel-15 PHY)
+├── openair2          : Layer 2 (3GPP LTE Rel-10 MAC/RLC/PDCP/RRC/X2AP, LTE Rel-14 M2AP, NR Rel-15+ MAC/RLC/PDCP/SDAP/RRC/X2AP/F1AP/E1AP), E2AP
+├── openair3          : Layer 3 (3GPP LTE Rel-10 S1AP/GTP, NR Rel-15 NGAP/GTP)
 ├── openshift         : OpenShift helm charts for some deployment options of OAI
-├── radio             : Drivers for various radios such as USRP, AW2S, RFsim, ...
+├── radio             : Drivers for various radios such as USRP, AW2S, RFsim, 7.2 FHI, ...
 └── targets           : Some configuration files; only historical relevance, and might be deleted in the future
 ```