Doc: Change wording on when module was introduced

Change to past tense.

Change-Id: I623ecbf4586b9212ceba5be15f18b0946b2de884
Reviewed-by: J-P Nurmi <jpnurmi@qt.io>

src/controls/doc/src/qtquickcontrols-index.qdoc

@@ -34,7 +34,7 @@
     The Qt Quick Controls module provides a set of controls that can be used to
     build complete interfaces in Qt Quick.
 
-    The module is new in Qt 5.1.
+    The module was introduced in Qt 5.1.
 
     Visit the \l{Qt Quick Controls Overview} page to get started.
 

src/controls/doc/src/qtquickcontrolsstyles-index.qdoc

@@ -62,7 +62,7 @@
 
     The Qt Quick Controls Styles submodule allows custom styling for \l {Qt Quick Controls}.
 
-    The submodule is new in Qt 5.1.
+    The submodule was introduced in Qt 5.1.
 
     \section1 Getting started
 

src/dialogs/doc/src/qtquickdialogs-index.qdoc

@@ -31,7 +31,7 @@
 
     \brief Qt Quick Dialogs submodule
 
-    The module is new in Qt 5.1.
+    The module was introduced in Qt 5.1.
 
     \section1 Dialogs