Document that Qt Script is deprecated

Change-Id: I0646c50ea17a71ae49b630ad1cb3ddb1c12d098d
Reviewed-by: Paul Wicking <paul.wicking@qt.io>

doc/src/scripting.qdoc

@@ -41,6 +41,10 @@ the integration should be, one of these APIs can be used:
  low level \l{ECMAScript Reference}{ECMAScript} engine API. Full documentation about using \l{Qt Script} to make an application
  scriptable can be found \l{Making Applications Scriptable}{here}.
 
+\warning This module is not actively developed. It is provided for backwards
+compatibility with Qt 4 only. For new code, use
+\l {JS API}{QJSEngine and related classes} in the Qt QML module instead.
+
 \section1 JS API
 This is a simple API, very similar to \l{Qt Script}, but limited to basic functionality. The main
  classes are QJSEngine and QJSValue, which can be used to embed pure \l{ECMAScript Reference}{ECMAScript} functionality