[css-contain] remove stray sentence

This is now redundant with text above.

Author: frivoal

css-contain-1/Overview.bs

@@ -300,8 +300,6 @@ Style Containment</h3>
 	When considering the effects of the scoped property on elements <em>inside</em> the subtree,
 	the element at the base of the subtree is treated as if it was the root of the document.
 
-	When scoped, the 'counter-set' and 'counter-increment' <a spec=css-lists-3>create a new counter</a>.
-
 	<div class=example>
 	As 'counter-increment' is scoped to an element's subtree,
 	the first use of it within the subtree acts as if the named counter were set to 0 at the scoping element,