doc(release): documentation for January 2023 v1.5 release

Signed-off-by: Raphael Defosseux <raphael.defosseux@openairinterface.org>

CHANGELOG.md

 # RELEASE NOTES: #
 
+## v1.5.0 -- January 2023 ##
+
+* Feature improvements:
+  * PDU SESS EST + Qos Monitoring events exposure
+  * Giving some time for FQDN resolution
+  * PFCP: removing dependency to folly
+  * Add IEs to support UE Rel 16
+  * Added and integrated UPF graph instead of PFCP associations list
+    * Supported scenarios:
+      - I-UPF / A-UPF N9
+      - UL CL
+  * Implement Npcf_SMPolicyControl API client
+  * Changing the configuration file to jinja2-based approach
+    * At least one slice (slice #0) shall be completely defined
+  * Ubuntu22 and cgroup2 support
+* Fixes:
+  * Fix openapi cause
+  * Fix small issue for Mime parser for normal message
+  * Fix Volume Threshold IE to PFCP Create URR IE
+  * Fix mcc mnc 00 udr
+  * Fix issues to work with Release-16 COTS UE
+  * Fix issue when there's no valid reply from UPF for PDU session release
+  * Fix Protocol identifier Selected Bearer Control Mode
+  * Fix issue for Static UE IP Addr
+* Docker image improvements
+  * Fixed docker exit by catching SIGTERM
+  * release mode does not use libasan anymore --> allocation of 20T virtual memory is no longer done
+
 ## v1.4.0 -- July 2022 ##
 
 * Fix for handling S-NSSAI 
 * Add support for IMS
 * HTTP/2 support for SBI interface
-* Add usage report feature
-* Flexiable MTU
+* Add usage reporting feature
+* Flexible MTU
 * Support for Ubuntu 20.04 bare-metal installation
 * Official images produced by CI are pushed to `oaisoftwarealliance` Docker-Hub Team account
 * Reduce image size