Plane: update release notes for 4.1.2

ArduPlane/release-notes.txt

@@ -1,7 +1,7 @@
-Release 4.1.2beta2 16th October 2021
-------------------------------------
+Release 4.1.2 17th October 2021
+-------------------------------
 
-This is beta update with minor fixes:
+This is minor update with a few important fixes and some new features:
 
  - added EK3_PRIMARY parameter, to allow for selection of other than
    the first IMU as initial EK3 lane
@@ -23,6 +23,9 @@ This is beta update with minor fixes:
 
  - fixed turn rate coordination when inverted in fixed wing flight
 
+ - fixed bug in AUTOTUNE mode that could leave gains from part way
+   through the tune
+
 Of these fixes the only one that is not backwards compatible is the
 new RC_OPTION bit which needs to be set if you have multiple RC
 receivers on your aircraft and want to fail over to a backup receiver
@@ -31,12 +34,6 @@ for the 4.1.2 release and later.
 
 Happy flying!
 
-Release 4.1.2beta1 10th October 2021
-------------------------------------
-
-This is beta update to test a fix to the AUTOTUNE code which can lead
-to bad gains being saved. We will release 4.1.2 stable shortly
-
 Release 4.1.1 stable 8th October 2021
 -------------------------------------