Update statement on GUI backward compatibility

hugo/content/gui/_index.md

@@ -14,7 +14,7 @@ and parameterize physical models, and to run fits.
 A graphical sample editor allows users to set up
 multilayer models. Model components like
 embedded particles or inter-particle correlation functions are
-represented by groupboxes with editable fields. Simultaneously, 
+represented by groupboxes with editable fields. Simultaneously,
 the real-space structure of the sample, or any of its components, can be
 shown in an interactive 3D visualization. This provides
 users with feedback as to whether the model, constructed
@@ -38,13 +38,8 @@ limits of GUI functionality to get started with using BornAgain
 from Python, since it is much easier to edit a given script
 than to write one from scratch.
 
-{{< alert theme="warning" >}}
-**Backward compatibility**
-
-We do not ensure that newer versions of BornAgain are able
-to read older versions of GUI project files. Such backward
-compatibility of project files will come at the earliest
-with release 2.0.
-{{< /alert >}}
+Until release 20.0, there was no mechanism to ensure backward
+compatibity. BornAgain 20 is not able to read GUI project files
+from older software versions.
 
 {{% children  %}}