[css-borders-4][editorial] Fix Bikeshed links to property value range (#13152)

Author: cdoublev

css-borders-4/Overview.bs

@@ -2478,7 +2478,7 @@ The 'border-clip' properties</h3>
 
 	<pre class="propdef shorthand">
 		Name: border-block-clip, border-inline-clip
-		Value: <'border-top-clip'>
+		Value: <<'border-top-clip'>>
 	</pre>
 
 	These two [=shorthand properties=] set the
@@ -2489,7 +2489,7 @@ The 'border-clip' properties</h3>
 
 	<pre class="propdef shorthand">
 		Name: border-clip
-		Value: <'border-top-clip'>
+		Value: <<'border-top-clip'>>
 	</pre>
 
 	'border-clip' is a [=shorthand property=] for the longhand properties,