Doc: update illustrations on front page

And on other pages. Use a two-column layout on the
Getting Started page to make it more readable in small
browser windows (in Qt Creator, for example).

Change-Id: I362b260305f8f66ae1796911e372858eeb5cc26f
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>

doc/src/overview/creator-getting-started.qdoc

@@ -34,8 +34,6 @@
         \row
             \li \inlineimage creator-gs-01.png
             \li \inlineimage creator-gs-02.png
-            \li \inlineimage creator-gs-03.png
-            \li \inlineimage creator-gs-04.png
         \row
             \li \b {\l{IDE Overview}}
 
@@ -46,6 +44,10 @@
 
                 If you have not used \QC before, and want to become familiar
                 with the parts of the user interface, go to \l{User Interface}.
+        \row
+            \li \inlineimage creator-gs-03.png
+            \li \inlineimage creator-gs-04.png
+        \row
             \li \b {\l{Building and Running an Example}}
 
                 To check that \l{glossary-buildandrun-kit}{kits} for building and running were