Update nanostack v12.7.0 changelog (ARMmbed#2525)

Author: Arto Kinnunen

CHANGELOG.md

@@ -2,24 +2,31 @@
 
 ## Release vxx.x.x
 
+### Features
+*
+
+### Changes
+*
+
+### Bugfix
+*
+
+## Release v12.7.0 (14-12-2020)
+
 ### Features
 * Use high priority for Wi-SUN maintenance messages to improve network stability under heavy load.
-* Limit network TX queue size under heavy load by using Random Early Detection for congestion avoidance.
-* Integrated Random early detection congestion packet drop to Wi-SUN interface.
+* Add Random Early Detection for congestion avoidance for Wi-SUN interfaces.
 
 ### Changes
-* Nanostack now indicates connection down on RPL local repair start
-* Added trace for mbed TLS errors
-* Optimized medium size network MPL parameters for 40 seconds multicast interval
-* Added traces to EAPOL TX failure
-* Added traces to Adaptation layer for Direct TX queue level decrease or increase by 20
-* New Network statistics info for Random early detection dropped packet at Adaptation layer.
-* Border router does not periodically increase the PAN version number for faster detection of Border router restart.
+* Nanostack indicates connection down event on RPL local repair start.
+* Optimized Wi-SUN medium size network MPL parameters for 40 seconds multicast interval.
+* Added Random Early Detection dropped packets field to network statistics.
+* Border router does not periodically increase the PAN version number for optimising Border router restart detection.
 
 ### Bugfix
-* Prevent sending broadcast frames on unicast channel
+* Prevent sending broadcast frames on unicast channel during heavy network traffic.
 * Delay sending of the first DIO message until parent selection is made and DAO target is published. Fix is made to avoid sending of DIO messages to the unstable network.
-* Accept only next possible BSI for detect BR reboot. This fix a bug when PAN timeout happen and node join correctly to new but hear old BSI after that.
+* Accept only next possible Broadcast Schedule ID to detect BR reboot situation.
 * Corrected radius message memory allocation by adding NULL check to recover from memory exhaustion.
 
 
@@ -28,7 +35,7 @@
 ### Features
 * Allow nanostack max trace level configuration
 * MPL parameters configured based on network size
-* Added faster recovery based on Broadcast schedule id change detection
+* Added faster recovery based on Broadcast Schedule ID change detection
 * Updated EAPOL relay target when attaching to the network
 
 ### Changes