remove double mention of $SRCDIR/src

Change-Id: I4627ba8d3be024ab982088fa58ad63c58d086280
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@nokia.com>

doc/config/qtcreator-project.qdocconf

@@ -2,7 +2,7 @@ project     = "Qt Creator"
 description = "Qt Creator Manual"
 
 headerdirs = 
-sourcedirs = $SRCDIR/src $SRCDIR/src
+sourcedirs = $SRCDIR/src
 imagedirs = $SRCDIR/images $SRCDIR/templates/images
 outputdir = $OUTDIR
 exampledirs = $SRCDIR