[css-overflow-4] Adjust example 6 to also work with continue:collapse

What it illustrating is equally applicable to continue:collapse and
continue:discard, but it was only written in terms of the latter.
Tweak the wording so that it applies to both.

Author: frivoal

css-overflow-4/Overview.bs

@@ -1083,22 +1083,31 @@ Fragmentation of Overflow: the 'continue' property</h3>
 			This keyword has no effect on [=multicol containers=].
 	</dl>
 
-	<div class=example>
-		Given an article with one excessively long overflowing line,
-		and four more lines than can fit in the [=fragmentation direction=] as in the illustration bellow,
+	<div class=example id=ex-continue-overflow>
+		Given,
+		 as in the illustration bellow,
+		an article with one excessively long overflowing line
+		and four more lines in the [=block dimension=] than can fit,
 		different renderings are possible based on the combination of the 'overflow' and 'continue' property.
 
 		<figure>
 		<img src="images/continue-flow.png" alt="article with one excessively long line and four more that can fit in the block direction">
 		</figure>
 
 
+		<style>
+#ex-continue-overflow td { text-align: center; }
+#ex-continue-overflow th:not(:first-child) { text-align: center; }
+		</style>
 		<table class=data>
+			<thead>
 			<tr>
 				<th>
-				<th>''continue: discard''
+				<th>''continue: collapse'' /
+					''continue: discard''
 				<th>''continue: auto''
 
+			<tbody>
 			<tr>
 				<th>''overflow: visible''