fix(htmlelement): clean 'inherit' concept in contentEditable (mdn#31935)

fix(htmlelement): clean 'inherit' concept

Co-authored-by: Estelle Weyl <estelle@weyl.org>

files/en-us/web/api/htmlelement/contenteditable/index.md

@@ -17,12 +17,13 @@ This enumerated attribute can have the following values:
 - '`true`' indicates that the element is `contenteditable`.
 - '`false`' indicates that the element cannot be edited.
 - '`plaintext-only`' indicates that the element's raw text is editable, but rich text formatting is disabled.
-- '`inherit`' indicates that the element inherits its parent's editable
-  status.
 
 You can use the {{domxref("HTMLElement.isContentEditable")}} property to test the
 computed boolean value of this property.
 
+If the attribute is missing or its value is invalid, its value is inherited from its parent element: so the element
+is editable (or not) based on the parent element.
+
 ## Value
 
 A string.