Docs: Document snippets for QtBridge plugins

Fixes: QDS-10177
Change-Id: Ibede8ffcaef6251c32cd78f7a90fb2f56f3a0824
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>
Reviewed-by: Pranta Ghosh Dastider <pranta.dastider@qt.io>

doc/qtdesignstudio/src/qtbridge/qtbridge-xd-using.qdoc

@@ -123,6 +123,17 @@
             antialiasing : true
             width: parent.width / 2
             \endcode
+        \li In the \uicontrol {Snippet} field, specify component to be added as child under this
+            component.
+            Following example adds a Connection component:
+            \code
+            Connections {
+                target: myItem
+                onVisibleChanged: console.log(original_Text.visible)
+            }
+            \endcode
+            \note The code must have a scope of a component(e.g. Item, MouseArea, Connections etc.)
+            with a valid syntax for \l {UI Files}.
         \li Select the \uicontrol Clip check box to enable clipping in the
             component generated from the layer. The generated component will clip
             its own painting, as well as the painting of its children, to its