[css-contain] Fix link

Author: frivoal

css-contain-1/Overview.bs

@@ -217,7 +217,7 @@ Layout Containment</h3>
 	layout containment has no effect.
 	Otherwise, giving an element <dfn export>layout containment</dfn> has the following effects:
 
-	1. The element <a>establishes a formatting context</a>.
+	1. The element establishes a new <a>formatting context</a>.
 
 	2. If a <a>fragmentation context</a> participates in <a>layout containment</a>,
 		the first element with <a>layout containment</a>
@@ -354,7 +354,7 @@ Paint Containment</h3>
 		<span class=note>This is as if to ''overflow: visible'' was changed to ''overflow: clip'' at used value.</span>
 	2. The element acts as a containing block for absolutely positioned and fixed positioned descendants.
 	3. The element creates a <a>stacking context</a>.
-	4. The element <a>establishes a formatting context</a>.
+	4. The element establishes a new <a>formatting context</a>.
 
 	Possible optimizations that can be enabled by <a>paint containment</a> include (but are not limited to):