Update Changelog.md

Author: MOARdV

Documents/Changelog.md

@@ -1,5 +1,28 @@
 ## Previous Releases of MOARdV's Avionics Systems
 
+### MAS 1.2.3
+For KSP 1.11.x, 21 May 2021
+
+**ATTENTION PLAYERS:** MAS includes a Module Manager patch that replaces all of the stock RPM props with MAS-enabled props.  If, for some reason, you do not want your RPM IVAs upgraded, you will need to rename GameData/MOARdV/Patches/JsiToMasUpgrade.cfg.
+
+**ATTENTION IVA MAKERS:** A number of MAS props (rotary switches, push buttons, toggle switches) were renamed so that MAS and ASET props have consistent naming conventions.  MAS includes an MM patch to update obsolete prop names in config files to their current names.  Some of the text layout on those props may have changed to be consistent with the ASET props style.
+
+**NOTE:** A partial ASET Avionics and ASET Props upgrade patch is included, but disabled.  To try it, please rename GameData/MOARdV/Patches/AsetToMasUpgrade.nocfg to GameData/MOARdV/Patches/AsetToMasUpgrade.cfg.  Currently, you will need RasterPropMonitor installed to enable any props that are not already updated.  There are no guarantees that partially-updated IVAs will work perfectly.
+
+#### Known Issues
+* Docking / undocking occasionally causes the MAS system to become unresponsive.  Changing scenes or switching to an unloaded vessel will reset it.
+* Map View lines occasionally are visible in MFD Camera views.  Issue #238.
+* KSP resets the reference transform when switching seats in IVA.  Issue #243.
+* The HORIZON MASMonitor component is not working correctly.  Issue #302.
+
+#### Fixes
+* Incorrect model paths for the 2m interior Spotlights have been fixed.
+
+#### New Features
+* Most of the remaining ASET Avionics props have been converted, courtesy a large contribution from vulkans22.
+* IVA for the OPT-J HT cockpit, courtesy vulkans22.
+
+---
 ### MAS v1.2.2
 For KSP 1.11.0, 19 December 2020.
 
@@ -945,4 +968,4 @@ For KSP 1.3.0 - KSP 1.3.1, released 5 Nov 2017.
 
 ---
 ### Pre-MAS v0.10.0
-Various development builds.
+Various development builds.