docs: Update help content for 2.9.0 (#412)

src/static/help.html

@@ -59,7 +59,11 @@ <h2>Features</h2>
 				<h2>What's new?</h2>
 				<p>New in version <span id="version"></span>&hellip;</p>
 				<ul>
-					<li><mark>TODO</mark></li>
+					<li>When moving forward or backward through landmarks, navigation now starts from the element that has the focus (if there is one). You can still skip directly to the "main" region, and to any of the other landmarks via the pop-up and/or sidebar.</li>
+					<li>Add the first linting feature for developers: open the DevTools panel and it will warn you about duplicate unlabelled landmarks.</li>
+					<li>Move the DevTools panel to the DOM/Element Inspector tab, so that you can see the HTML and landmarks side-by-side.</li>
+					<li>Softer update notifications&mdash;when the extension is updated, instead of opening a new page, badge the browser toolbar button and include a note in the pop-up and/or sidebar.</li>
+					<li>Enhanced performance tests, so that the code can be kept as snappy as possible.</li>
 					<li><strong>Edge users:</strong> version 2.8.0 was not available for Edge due to an issue with the system used for uploading extensions. The Edge team is looking into it, and I've developed a work-around, so we are back on now. Please <a href="https://github.com/matatk/landmarks/blob/master/CHANGELOG.md#280-2020-07-25">check out what was new in version 2.8.0</a> so that you don't miss out on any of the info.</li>
 				</ul>
 				<p>For full details, consult the <a href="https://github.com/matatk/landmarks/blob/master/CHANGELOG.md#changelog">change log</a>.</p>