Merge pull request #173 from ckeditor/t/ckeditor5/1591

Other: Introduce editor-wrong-element error thrown when editor is created over wrong element. Closes ckeditor/ckeditor5#1591.

src/editor/editor.js

@@ -312,6 +312,22 @@ mix( Editor, ObservableMixin );
  * @event destroy
  */
 
+/**
+ * This error is thrown when a user tries to use a `<textarea>` element to create a non-classic editor in it.
+ *
+ * Textarea element represents a plain-text and cannot be used as a editable root element with included CKEditor5.
+ * Content of an editor should be nicely present to the user and show him how it's going to looks like. Textarea element
+ * doesn't support such behavior.
+ *
+ * Only {@glink builds/guides/overview#classic-editor Classic Editor} has implemented a special system, which
+ * **replace** DOM element and load data from it
+ * ({@link module:editor-classic/classiceditor~ClassicEditor.create more information}). All other editors
+ * use an existing element, load data from it and make this element editable. Details about behaviour of each editor
+ * might be found in an associated description of a `create` method of each editor.
+ *
+ * @error editor-wrong-element
+ */
+
 /**
  * An array of plugins built into this editor class.
  * It is used in CKEditor 5 builds to provide a list of plugins which are later automatically initialized