Merge pull request #1324 from kategengler/kg-note-ember-string-bug

Add a warning about the current bug in the implementation of the `@ember/string` deprecation.

Author: jenweber

content/ember/v4/deprecate-ember-string.md

@@ -19,3 +19,13 @@ To add the package to your project:
 If you were importing `htmlSafe` or `isHTMLSafe` from `@ember/string`, please
 import them from `@ember/template` instead. See
 [this deprecation guide](https://deprecations.emberjs.com/v3.x#toc_ember-string-htmlsafe-ishtmlsafe) for more information.
+
+Note! As of May 19, 2023 there is a [bug](https://github.com/emberjs/ember.js/issues/20377) 
+in the implementation of the `@ember/string` deprecation. Adding `@ember/string` 
+to your project may not be enough to silence the deprecation. You may silence 
+the deprecation by using [`ember-cli-deprecation-workflow`](https://github.com/mixonic/ember-cli-deprecation-workflow). 
+
+To upgrade to `ember-source v5.0`, ensure that `@ember/string` has been added
+to your project, and even if you still see this deprecation warning on `v4.x`, imports from
+`@ember/string` will continue to work and no longer display a deprecation warning
+once on `v5.x`.