Added accessibility tags

Author: wobba

src/controls/webPartTitle/WebPartTitle.tsx

@@ -49,7 +49,7 @@ export class WebPartTitle extends React.Component<IWebPartTitleProps, {}> {
           }
 
           {
-            this.props.displayMode !== DisplayMode.Edit && this.props.title && <span>{this.props.title}</span>
+            this.props.displayMode !== DisplayMode.Edit && this.props.title && <span role="heading" aria-level="2">{this.props.title}</span>
           }
         </div>
       );