Update css-overflow-4/Overview.bs

Co-authored-by: Florian Rivoal <[email protected]>

Author: andreubotella

css-overflow-4/Overview.bs

@@ -1153,7 +1153,7 @@ Fragmentation of Overflow: the 'continue' property</h3>
 
 	Additionaliy,
 	for compatibility (see [[#webkit-line-clamp]]),
-	when the [=computed value=] of the 'continue' property is ''collapse'' or ''-webkit-collapse''
+	when the [=computed value=] of the 'continue' property is '''collapse'', ''-webkit-collapse'', or ''discard''
 	and the [=computed value=] of the '-webkit-box-orient' property is ''vertical'':
 	* If the [=specified value=] of the 'display' property is ''-webkit-box'',
 		the [=computed value=] becomes ''flow-root'' and