Doc: Fix example for QT_DEPLOY_TRANSLATIONS_DIR

The shared example for modifying deployment directory variables now sets
QT_DEPLOY_TRANSLATIONS_DIR too.

Also, add the missing install(SCRIPT) call.

Pick-to: 6.5
Fixes: QTBUG-113216
Change-Id: I6d52d946a21f006ae6222de1211f3d239bd03fc4
Reviewed-by: Orkun Tokdemir <orkun.tokdemir@qt.io>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

src/corelib/doc/src/includes/cmake-deploy-modified-variable-values.qdocinc

@@ -15,10 +15,13 @@ file(GENERATE OUTPUT ${deploy_script} CONTENT "
 
 set(QT_DEPLOY_PLUGINS_DIR \"mypluginsdir\")
 set(QT_DEPLOY_QML_DIR \"myqmldir\")
+set(QT_DEPLOY_TRANSLATIONS_DIR \"i18n\")
 
 include(\"${QT_DEPLOY_SUPPORT}\")
 
 qt_deploy_runtime_dependencies(
     EXECUTABLE \"\${QT_DEPLOY_BIN_DIR}/$<TARGET_FILE_NAME:MyApp>\"
 )")
+
+install(SCRIPT ${deploy_script})
 \endcode