Update the demo images

examples/xlsx/demo/doc/src/demo.qdoc

@@ -4,9 +4,5 @@
     \brief This is a demo which is used to show features of the library
     \ingroup qtxlsx-examples
 
-    \image xlsx_demo.png
-    \image xlsx_demo_fonts.png
-    \image xlsx_demo_formulas.png
-    \image xlsx_demo_merging.png
-    \image xlsx_demo_grouping.png
+    \image xlsx_demo.gif
 */

examples/xlsx/demo/main.cpp

@@ -289,8 +289,8 @@ int main()
     xlsx.saveAs("Book1.xlsx");
 
     //Make sure that read/write works well.
-    Document xlsx2("demo.xlsx");
-    xlsx2.saveAs("demo2.xlsx");
+    Document xlsx2("Book1.xlsx");
+    xlsx2.saveAs("Book2.xlsx");
 
     return 0;
 }

src/xlsx/doc/src/qtxlsx-index.qdoc

@@ -37,7 +37,7 @@
        \li Edit an existing .xlsx file
     \endlist
 
-    \image xlsx_demo.png
+    \image xlsx_demo.gif
 
     \table
       \row