Add \since 5.4 to FontMetrics and TextMetrics.

Change-Id: I5fa93d559cdfde5e6b84ab0f3f35fd600e6bec4f
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>

src/quick/util/qquickfontmetrics.cpp

@@ -41,6 +41,7 @@ QT_BEGIN_NAMESPACE
     \qmltype FontMetrics
     \instantiates QQuickFontMetrics
     \inqmlmodule QtQuick
+    \since 5.4
     \ingroup qtquick-text-utility
     \brief Provides metrics for a given font
 

src/quick/util/qquicktextmetrics.cpp

@@ -41,6 +41,7 @@ QT_BEGIN_NAMESPACE
     \qmltype TextMetrics
     \instantiates QQuickTextMetrics
     \inqmlmodule QtQuick
+    \since 5.4
     \ingroup qtquick-text-utility
     \brief Provides metrics for a given font and text