Update index.html

fix typo

Author: giacomo-petri

index.html

@@ -16161,7 +16161,7 @@ <h2>Including Elements in the Accessibility Tree</h2>
         <h2>Relationships in the Accessibility Tree</h2>
         <p>The following terms are used to describe relationships between <abbr title="Document Object Model">DOM</abbr> elements.</p>
         <p>
-          The <dfn data-export="" data-lt="accessibility anestor|accessibility ancestors">accessibility ancestors</dfn> of a DOM element are all DOM elements of which the given DOM element is an
+          The <dfn data-export="" data-lt="accessibility ancestor|accessibility ancestors">accessibility ancestors</dfn> of a DOM element are all DOM elements of which the given DOM element is an
           <a>accessibility descendant</a>.
         </p>
         <p>