Update MergePptx settings for 8.1.0

docx4j-samples-resources/src/main/resources/docx4j.properties

@@ -330,13 +330,17 @@ com.plutext.merge.BookmarkRenaming=true
 
 # MergePptx setup
 # ^^^^^^^^^^^^^^^
-# AlternateContent needs to be removed from the Slides.
-# If it isn't, Powerpoint 2010 might complain that the presentation
-# needs to be repaired.
-# docx4j 3.0 does this (actually, nightlies post 2013 04 29).  But if you are using
-# docx4j 2.8.1 (or a nightly earlier than 2013 04 29), then setting this to
-# true will have MergePptx do it.  Default is false. 
-MergePptx.AlternateContentFallback=true
+# Obsolete setting: In older docx4j, AlternateContent had to be removed from the Slides.
+# (This is not necessary with 8.1, and may not have been necessary with recent earlier releases either)
+# If it wasn't, Powerpoint 2010 might complain that the presentation needs to be repaired.
+# docx4j 3.0 did this;  But if you are using docx4j 2.8.1, then setting this to
+# true will have MergePptx do it.  Default is false.
+# MergePptx.AlternateContentFallback=true
+
+# PowerPoint 2010 introduced the concept of sections (p14:sectionLst)
+# Set this property to true if you want to retain sections (default is false)
+# (since 8.1.0)
+com.plutext.merge.pptx.SectionAware=false
 
 # XML Dig Signature setup
 # ^^^^^^^^^^^^^^^^^^^^^^^