added a note about the annotation editor

extension/ui/pages/help.html

@@ -52,6 +52,8 @@
 							<li>or all the tabs.</li>
 						</ul>
 					</li>
+					<li>You can annotate the page before saving it by selecting "Annotate and save the page..." in the
+						context menu.</li>
 					<li>You can interrupt the saving progress by clicking on the SingleFile button when processing a
 						page.</li>
 					<li>With auto-save active, pages are automatically saved every time after being loaded (or before