[RPP] Add 'Create label on Enter' to the annotations tutorial

Bug: 406998698
Change-Id: Id678f2962e3e0ddc3e8afb44c55456b219631191
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6439015
Reviewed-by: Jack Franklin <jacktfranklin@chromium.org>
Commit-Queue: Jack Franklin <jacktfranklin@chromium.org>
Auto-Submit: Alina Varkki <alinavarkki@chromium.org>

Author: AlinaVarkki

front_end/panels/timeline/components/SidebarAnnotationsTab.ts

@@ -41,7 +41,7 @@ const UIStrings = {
   /**
    * @description Text for how to create an entry label.
    */
-  entryLabelTutorialDescription: 'Double-click on an item and type to create an item label.',
+  entryLabelTutorialDescription: 'Double-click or press Enter on an item and type to create an item label.',
   /**
    * @description  Title for diagram.
    */