Doc: Whitespace fix.

Change-Id: Ie088da27231c41a43f57f681723c80d07960b331
Reviewed-by: Sergio Ahumada <sergio.ahumada@digia.com>
Reviewed-by: Martin Smith <martin.smith@digia.com>

doc/src/platforms/qtmac-as-native.qdoc

@@ -32,7 +32,7 @@
 
     This document explains what makes an application native on Mac OS X.
     It shows the areas where Qt is compliant, and the grey areas where
-    compliance is more questionable. (See also the document 
+    compliance is more questionable. (See also the document
     \l{mac-differences.html}{Qt for Mac OS X - Specific Issues}.)
 
     Normally when referring to a native Mac application, one really means an