DOC: show the ddp3 filename extension change in README.

dragonyanglong · dragonyanglong · commit 3edea21bf686 · 2021-12-20T23:02:50.000+08:00
diff --git a/README.rst b/README.rst
@@ -48,6 +48,10 @@ installed using ::
 To install the remaining packages see the installation instructions
 at their respective web pages.
 
+The Python3 PDFgui project filename extension has been changed to .ddp3.
+Please note that sometimes it may fail for .ddp project files that were
+saved by the Python2 PDFgui to be read by Python3 PDFgui. We are working
+on a solution that will be available in a future version.
 
 INSTALLATION
 ------------------------------------------------------------------------
