Editorial - Removed "or" at the beginning of the list of allowed roles for "form" element (#500)

Co-authored-by: Scott O'Hara <[email protected]>

Author: giacomo-petri

index.html

@@ -1343,7 +1343,7 @@ <h2 id="docconformance">
             <td>
               <p>
                 Roles:
-                or <a href="#index-aria-none">`none`</a>,
+                <a href="#index-aria-none">`none`</a>,
                 <a href="#index-aria-presentation">`presentation`</a>
                 or <a href="#index-aria-search">`search`</a>. (<code><a href="#index-aria-form">form</a></code> is also allowed, but NOT RECOMMENDED.)
               </p>