description improved

frontend-js/src/main/js/gui/leftPanel/OverlayPanel.js

@@ -426,7 +426,7 @@ OverlayPanel.prototype.openAddOverlayDialog = function() {
   content.appendChild(fileInput);
   content.appendChild(guiUtils.createNewLine());
 
-  content.appendChild(guiUtils.createLabel("Or provide list of elements here: "));
+  content.appendChild(guiUtils.createLabel("Or provide list of elements here (one per line): "));
   content.appendChild(guiUtils.createNewLine());
   contentInput = guiUtils.createTextArea();
   content.appendChild(contentInput);