When we added the link to the webrev comment in the PR body, for some reason it got its own header "### Webrev". But Webrevs are just another way of reviewing, so it should be put under the "### Reviewing" header.

That is, the reviewing html code should look something like this:
"
...
<details><summary>Using diff file</summary>

Download this PR as a diff file: \
<a href="https://git.openjdk.org/jdk/pull/XXX.diff">https://git.openjdk.org/jdk/pull/XXX.diff&lt;/a>

</details>
<details><summary>Using Webrev</summary>

[Link to Webrev Comment](https://git.openjdk.org/jdk/pull/XXX#issuecomment-YYY)

</details>
"