Update readme.txt for version 3.4.3

readme.txt

@@ -7,7 +7,7 @@ Miro Dudik          ([email protected])
 Steven Phillips     ([email protected])
 Rob Schapire        ([email protected])
 
-Version 3.4.2, April 2017
+Version 3.4.3, November 2020
 
 This file outlines the steps you should take to begin using maxent to
 model species geographic distributions.  To download the program, or
@@ -118,6 +118,11 @@ click on the maxent.bat file instead.  If this is not the problem,
 click on the "help" button for more advice.
 
 
+Main Changes in Version 3.4.3:
+-----------------------------
+   Fixed a bug that was causing abrupt changes in response curves for some floating -point predictor variables,
+     due to the "add samples to background" option not adding all samples for floating-point predictors.
+
 Main Changes in Version 3.4.2:
 -----------------------------
    Fixed bug that causes nodoclamp flag not to work for dismo's predict method for MaxEnt objects