Spell "Qt" correctly

Change-Id: Idf2b5c888f159ee8ffdb81ed74e685c40951c6b4
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>

src/corelib/doc/snippets/qstring/main.cpp

@@ -856,7 +856,7 @@ void Widget::toLongLongFunction()
 void Widget::toLowerFunction()
 {
     //! [75]
-    QString str = "The QT PROJECT";
+    QString str = "The Qt PROJECT";
     str = str.toLower();        // str == "the qt project"
     //! [75]
 }