Use qsTr() for user facing strings in particle attractors example

Pick-to: 6.5
Change-Id: I8025b5dde59706827cb1bf546d03c6088f4600de
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

examples/quick/particles/affectors/wander.qml

@@ -45,15 +45,15 @@ Rectangle {
         anchors.horizontalCenter: parent.horizontalCenter
         spacing: 4
         GreyButton {
-            text:"dx/dt"
+            text: qsTr("dx/dt")
             onClicked: wanderer.affectedParameter = Wander.Position;
         }
         GreyButton {
-            text:"dv/dt"
+            text: qsTr("dv/dt")
             onClicked: wanderer.affectedParameter = Wander.Velocity;
         }
         GreyButton {
-            text:"da/dt"
+            text: qsTr("da/dt")
             onClicked: wanderer.affectedParameter = Wander.Acceleration;
         }
     }