[css-contain-1] Clarify comment about available tests

Author: frivoal

css-contain-1/Overview.bs

@@ -88,8 +88,11 @@ Strong Containment: the 'contain' property</h2>
 
 		<details>
 			<summary>This change has tests</summary>
-			<a href="https://github.com/web-platform-tests/wpt/commit/98c4e2d52402156bfafcd1466985b5336f6c7240">Tests for this change</a> have been added to <abbr title="Web Platform Tests">WPT</abbr>.
-			The results can be viewed at <a href="https://wpt.fyi/results/css/css-contain/parsing/contain-computed.html">wpt.fyi</a>
+			A <a href="https://github.com/web-platform-tests/wpt/commit/98c4e2d52402156bfafcd1466985b5336f6c7240">test for this change</a> has been added to <abbr title="Web Platform Tests">WPT</abbr>.
+			The results can be viewed at <a href="https://wpt.fyi/results/css/css-contain/parsing/contain-computed.html">wpt.fyi</a>.
+			Note that a few subtests of this test
+			(those involving the <code>style</code> or <code>inline-size</code> values)
+			only relate to later levels of this specification.
 		</details>
 	</div>