Update index.html

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

index.html

@@ -3267,7 +3267,7 @@ <h4 id=el-img-empty-alt>`img` <span class="el-context">(`alt` attribute value is
       <td>
         <a data-cite="html">`img`</a>
         <span class="el-context">(<a data-cite="html/embedded-content.html#attr-img-alt">`alt`</a>
-                attribute value is the empty string, i.e. `alt=""` or `alt` with no value in the markup)</span>
+                attribute value is the empty string, i.e., `alt=""` or `alt` with no value in the markup)</span>
       </td>
     </tr>
     <tr>