Add explanation for retaining HTML reports across test runs.

docs/guide/configuration/customising-test-output.md

@@ -28,7 +28,7 @@ The below settings can be used to control the output and logging when running te
      <td><code>folder_format</code></td>
      <td>string/function</td>
      <td>undefined</td>
-     <td>Used as a prefix for HTML report folder. This can be utilised to retain HTML report across test runs</td>
+     <td>Used as a prefix for HTML report folder. This can be utilised to [retain HTML report across test runs](https://github.com/nightwatchjs/nightwatch-docs/issues/310#issuecomment-2233833015)</td>
    </tr>
 
    <tr>
@@ -112,4 +112,4 @@ The below settings can be used to control the output and logging when running te
         <span>→</span>
     </a>
   </div>
-</div>
+</div>