Update html-page-lang-b5c3f8.md

Author: giacomo-petri

_rules/html-page-lang-b5c3f8.md

@@ -34,7 +34,10 @@ This rule applies to any [document element](https://dom.spec.whatwg.org/#documen
 
 - is in a [top-level browsing context](https://html.spec.whatwg.org/#top-level-browsing-context); and
 - has a [node document](https://dom.spec.whatwg.org/#concept-node-document) with a [content type](https://dom.spec.whatwg.org/#concept-document-content-type) of `text/html`; and
-- has at least one [descendant](https://dom.spec.whatwg.org/#concept-tree-descendant) [text node][] which is neither empty nor only [whitespace][]..
+- has at least one of the following [descendant](https://dom.spec.whatwg.org/#concept-tree-descendant) that is not empty or only [whitespace][]:
+	- [text node][] that is included in the accessibility tree; or
+ 	- an element's [accessible name][] or [accessible description](https://www.w3.org/TR/accname-1.1/#dfn-accessible-description) that is exposed in the accessibility tree; or
+  	- the document's title.
 
 **Note:** `html` elements within `iframe` and `object` elements are not applicable as `iframe` and `object` elements create [nested browsing contexts](https://html.spec.whatwg.org/#nested-browsing-context). However, as these elements are meant to provide a layer of isolation, the declared language of their [parent browsing context](https://html.spec.whatwg.org/#parent-browsing-context) will likely not be inherited, making it possible for empty `lang` attributes in [nested browsing contexts](https://html.spec.whatwg.org/#nested-browsing-context) to also cause accessibility issues.