[Editorial] - [a25f45] Headers attribute specified on a cell refers to cells in the same table element - Inapplicable Example 4 improvement (#2244)

* Added aria-label to the role="table" element

* Update _rules/table-headers-attribute-refer-to-data-cells-a25f45.md

Co-authored-by: Carlos Duarte <carlosapaduarte@gmail.com>

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Co-authored-by: Carlos Duarte <carlosapaduarte@gmail.com>

Author: giacomo-petri

_rules/table-headers-attribute-refer-to-data-cells-a25f45.md

@@ -371,7 +371,7 @@ The `table` is not [visible][] in page.
 The rule applies only to `headers` attribute within a `table` element.
 
 ```html
-<div role="table">
+<div role="table" aria-label="Grades">
 	<div role="row">
 		<div role="columnheader" id="header1">Projects</div>
 		<div role="columnheader" id="header2">Exams</div>