Doc: Setting landing page variable

Change-Id: Ib1f9c6a130d800c96eff5537d2367e2a6ca07c4c
Reviewed-by: Martin Smith <martin.smith@digia.com>
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

src/activeqt/doc/activeqt.qdocconf

@@ -44,3 +44,5 @@ exampledirs += ../../../examples/ \
                snippets
 
 imagedirs   += images
+
+navigation.landingpage = "Active Qt"