[css-contain-3][editorial] Add context to matchContainer issue

Author: mirisuzanne

css-contain-3/Overview.bs

@@ -378,8 +378,6 @@ Container Queries</h2>
 		</pre>
 	</div>
 
-	Issue(6205): Container Queries should have a matchContainer method
-
 <h3 id="container-type">
 Creating Query Containers: the 'container-type' property</h3>
 
@@ -997,6 +995,12 @@ The <code>CSSContainerRule</code> interface</h3>
 
 	Issue(7033): Add CSSOM API for CSSContainerRule
 
+	Issue(6205): Container Queries should have a <code>matchContainer</code> method.
+	This will be modeled on {{matchMedia()}} and the {{MediaQueryList}} interface,
+	but applied to Elements rather than the Window.
+	When measuring layout sizes, it behaves Similar to <code>resizeObserver</code>,
+	but it provides the additional Container Query syntax and features.
+
 Suppressing An Element’s Contents Entirely: the 'content-visibility' property {#content-visibility}
 =================