[css-contain-2] Editorial: solve a cross-reference issue

Use the explicit name of the event in the prose so that references to it
have somewhere to resolve. Also reorder things slightly.

Author: frivoal

css-contain-2/Overview.bs

@@ -1690,9 +1690,15 @@ Using ''content-visibility: auto''</h3>
 		will be forced to rely on the ''200px'' height estimate.
 	</div>
 
-Detecting ''content-visibility: auto'' state changes: the 'ContentVisibilityAutoStateChanged' event {#content-visibility-auto-state-changed}
+Detecting ''content-visibility: auto'' state changes: the <a event>contentvisibilityautostatechanged</a> event {#content-visibility-auto-state-changed}
 --------------------------------------------------------------------------------------------------------------------------------------------
 
+The <dfn event dfn-for="Element">contentvisibilityautostatechanged</dfn> event is fired on an element with ''content-visibility: auto'' style when
+the rendering state changes and the element either becomes or stops being
+[=relevant to the user=].
+
+This event is dispatched by posting a task at the time when the state change occurs.
+
 <pre class='idl'>
 [Exposed=Window]
 interface ContentVisibilityAutoStateChangedEvent : Event {
@@ -1722,12 +1728,6 @@ Description of ContentVisibilityAutoStateChangedEventInit members:
 
 </div>
 
-This event is fired on an element with ''content-visibility: auto'' style when
-the rendering state changes and the element either becomes or stops being
-[=relevant to the user=].
-
-This event is dispatched by posting a task at the time when the state change occurs.
-
 Note: elements in ''content-visibility: auto'' subtrees remain semantically
 relevant even for elements that [=skip its contents=]. This means that it is
 inappropriate to use this signal to indefinitely skip DOM updates in the